Two items (generator and adding weight/hitch to frame)
Generator - we just took the Kohler generator out of our 93 Itasca (likely the same setup, compartment behind the Driver's door on side of Motorhome). One thing we learned is that the wiring harness is actually plugged together where it goes through the compartment wall (no need to remove any wires at either end which is fairly slick and wish we knew before(!). You need to disconnect battery (for safety while doing the work) and then remove that lead from the starter solenoid on the generator (and either completely remove or carefully insulate and strap this wire so it won't ground/short out - that is what we did in case we decide to add another battery to store more electricity from our solar system). The generator is held on with 4-5 bolts, we drilled out a 2 inch piece of wood to accomodate the generator housing on bottom and distribute load away from that bearing housing (using a floor jack). Drove moho onto ramps, then disconnected fuel line and sealed (still need to fully remove) and then with two people carefully removed bolts while floor jack held it in place and lowered and pulled out generator - not too hard but may need to tilt to get out (away from oil filler and carberator to avoid spillage).
For now, I just attached 3 angle iron type metal pieces to the old bolt locations and cut out a board to fit (about 15 x 17 inches if I recall - note that it might not be square) - I left the dividers in for now as it seems to fit my jacks, small propane tank, levelling boards and extension cord (I greatly reduced the original one as heavy and I don't run A/C and microwave at same time!). I was thinking of making it larger but the previous owner had blocked up the storage under the dinnette that will accomodate longer/larger items and I found that our folding chairs fit neatly behind drivers seat (I am short so room there).
Weigth/hitch on frame - previous owner had built a large box and had weldled brackets to hold above rear bumper (which I believe is aluminum and can't take any weight or may fall off with your cargo). Anyways, I beefed this up to carry a spare tire and spent a lot of time re-inforcing, building attachment brackets inside box to safely carry tire, propane tank, etc... Loaded it on and filled it with tire, etc.. now likely weighing 150 lbs... Well before I drove off I am glad I noticed some movement when closing the lid - it (rear frame at bumper area) seemed to easily go up and done about 1/2 inch with me pulling it up and down. This is not good as you can fatigue welds, metal, etc... so I removed it and am now storiing items as discussed above and will mount spare tire deep underneath in original Toyota location (both yielding better load balance anyways). I have made a bike mount for the rear bumper brackets and have put my bike there (35 lbs, which someone at Winnebago service dept said should be fine and does not move up and down much at all).
So, the short of it (sorry if long winded here), is that the frame is likely adequate for the stock configuration but add much weight or a hitch and it likely needs beefing from the original truck frame back. Might not hurt to have someone check frame periodically - I am getting this done after realizing that 15 years of heavy box action might not be that good.
The other issue is overloading your unit, ours only has a GVWR of 6,000 lbs so you will likely definitely be over... check out what this means for insurance, motor vehicle dept, etc...
hope this helps, cheers from Desert nomad...