Hi Jim,
Reason I mentioned Steinbeck, is that in his book "Travels with Charley" he recounts his trip around the US in a truck camper with his dog, Charley. The truck camper (early days!) was named "Rocinante." 'course it may be for an entirely different reason if your spouse is not a fan.
On the towing: I tow often (boat/trailer, cargo trailer, tow car) although one slight difference is that I have the manual rear steps. But it's not that different.
So, the first think I would do is hop over to etrailer and look for their "long," "extra long," and "extra, extra long" ball mounts (that's what they call the part that fits into the receiver hitch and takes the ball). Obviously you want the shortest one you can use, but these are better than hitch extensions. I know that one of the longer ones will work even for the electric step version of the 21' Chinook. etrailer often has the measurements on the page, but if not, look down in the comments, or in the Q & A tab, and you might find them there. If not, you can write in and ask. They will go and measure for you (very nice), which is why you may already find the info in a comment or answer from someone else. They have the best selection I have found.
The critical dimension is from pin hole to wherever the 2" square tubing has its first projection (which may vary depending on how much drop or rise you need). I tend to need a rise to keep my tandem trailer level, and a different rise for the cargo trailer (not as important since it's single axle, but I still like it level), and then I'm fine as is (no drop or rise) for the car towing, but that all depends on the level of the baseplate on a particular car. In fact, I decided not to tow the CR-V I was considering because it had a very high baseplate height (where the "prongs" come out of the grille) and I would have needed a huge riser. Went with a Subaru instead which is within an inch of the Chinook hitch (on my rig).
Sounds like you are experienced towing (so don't be offended if this is all old news), but if not, one thing to know is that the "tow rating" (aka GCWR) is pretty much pointless on our rigs. Here's why I say that, giving my 21' Concourse as an example:
So here are the various ratings on my rig:
1) GVWR (gross vehicle weight rating): 10,700#. So my rig and all its contents, plus driver and any passenger, can't weigh over 10,700# to stay within ratings.
2) GAWR-F (gross axle weight rating, front axle): 3,700#
3) GAWR-R (gross axle weight rating, rear axle): 7,500#
4) GCWR (gross combined weight rating): an "impressive" 18,000#. So you'd think you could tow a house! But....
As my rig sits, with a relatively minimal amount of "stuff" in it, plus me, weighed around a dozen times at different scales (usually pretty similar). I'll take October 2014 for my example since I wasn't towing. I also weighed at almost an empty gas tank, then filled it up and drove back to the scale (gas tank on my rig is behind rear axle, so affects it). The return numbers are in parenthesis.
GVW, me, 1/2 propane, empty water tank, empty black tank, 5 gallons in grey tank, 1/8 gas tank (full gas tank) = 10,250# (10,400#)
GAW-F = 3,450# (3,450#)
GAW-R = 6,800# (6,950#)
GCW = N/A
As you can see there, I'm all within ratings. About 250# below on the front axle, about 800# below on the rear axle, and about 400# below on the gross vehicle weight rating. Now supposedly there is nearly 8,000# "left over" for my gross combined rating. Yeah, sure! As I'm sure you can already see, it's the rear axle weight rating that is going to be the "stopper," and that'll be long before I'm towing 8,000#.
Not only is there tongue weight (when towing a trailer), but because of the long overhang, the tongue weight is multiplied on the rear axle. I have a formula that I used, and it was nearly spot on when I actually weighed when towing my boat/trailer. But just to give you the numbers as an example, my boat/trailer weighs around 4,600# all up. Since it's a tandem, I can reduce tongue weight as compared to a single, and run 5-7% tongue weight (vs. 10%). So I end up with just over 300# of tongue weight. BUT, that actually adds closer to 550# of tongue weight to the rear axle. That puts me up close to the rear axle limit. Close is fine, and a bit over probably isn't going to break anything, but you can see that there's no way I'm going to nearly DOUBLE the trailer and tongue weight (for the hypothetical 8,000# trailer) and be anywhere but sky high over the ratings. So to my mind, 5,000# is my practical towing limit with my rig. I knew that going in, and I'm fine with that.
Of course "four down" tow cars don't have tongue weight, but I'd be surprised if the receiver itself would be happy at 8,000# (it could be beefed up though). But likely few people are interested in towing an 8,000# tow car with a Chinook.
So why have an 18,000# GCWR? Well, these are cutaway E-350's (or the equivalent Chevy or maybe E-450), and so as far as Ford is concerned, you may just throw a lightweight service body on it. In that case, maybe the GCWR would be more appropriate. But throw a heavyish RV body on, with tankage, people, stuff, etc. and that's a pipedream.
Of course this may not apply exactly to your rig, but you get the idea. There should be a Ford sticker on the driver's door jamb that gives you the weights. That, combined with a scale weight and some math will result in your own specific rig's limits. I can post the formula and/or do the math for anyone who is interested. What's needed is the tongue weight of the trailer, the distance between the hitch ball and the rear axle, and the wheelbase (distance from rear axle to front axle).
Hopefully not too much info (and again, if this is all old hat, sorry but I didn't know) - but there is always the scroll button
