1996 fleetwood bounder questions
Have you tried contacting Fleetwood directly and posing this question to their engineering department?
One clue for the low limit might be to take the RV to a truck scale and measuring the axle loads--preferably with it loaded the way you plan to travel, and see how close the rear axle is to be maxed out. Keep in mind that tongue weight on an RV with such a long overhang will put considerably more weight on the rear axle, while lightening the front axle somewhat. To simulate, have 2 or three people stand on the rear bumper or in the very rear of the motorhome and see how the axle weights change on the scale (this will probably cost you another weighing fee, but what the hell).
The good thing about a toad is that it has almost no hitch weight to it, as opposed to a trailer.
I've seen people pull trailers about the size you are talking about with Bounders, but I don't know the specifics.