Kevin,
Please keep in mind the need to keep the weight down in the '50's models.
One of our more active members did not and overloaded the front of his
trailer. He got away with it for a while, but now is looking at frame repair
or replacement. Don't remember which year exactly, but I think it was mid a
50's 22 footer. If you want much more than 20 gal fresh water I would
suggest putting it as close to the axle as possible. Wherever you place the
gray & black tanks remember to dump them before moving, or as soon as
possible (IE the campground dump station).
Scott