I have installed a Generac 3.5KVA propane generator in a 1973 Sovereign
31ft. trailer. It is in the space in front of the trailer under the setee. I constructed a frame for it in the space where the spare tire would normally be mounted, then built a box out of 3/4 plywood lined with galvanized sheet metal to cover it. I lost two of the slide out trays in the process, but am happy with the tradeoff. The floor is cut so that air can enter for cooling and engine air intake. The exhaust exits under the propane tanks in the a- frame. I upgraded to 40 lb tanks. It is quiet enough to be comfortable with the air running and all of the other entertainment equipment.
This generator would not operate the orginal Armstrong AC unit. Though that unit worked ok with shore power, the 3.5KVA unit could not run it. I changed the AC to a newer unit and everything works fine. Seemed I was overdue for that.