We have a
Scamp 16. I installed a microwave that hangs under a galley cabinet. the microwave wasn't intended to be mounted that way.
I went to Walmart and hefted the microwaves in the box. Quite a difference and the lightest turned out to be the cheapest and small. Still, it is fine for microwave dinners, hot beverages, nuking potatoes and heating left-overs. I did this job about 3 - 4 years ago and have pulled the trailer close to 20,000 miles, sharp winding roads in the rockies, many national park roads and washboard freeways in Indiana.
The key to hanging a lite microwave is to remove the metal bonnet and fabricate a reinforcement. I took 2 lengths of 1" metal flat stock, positioned it under the bonnet and through bolted it to the cover. The screws were about #10 x 1" and I used 4 to a side or length of flatstock. Pay attention as to where the heads will live with the bonnet installed. They don't have to be perfectly spaced. Put a locknut or lock washer and nut on the outside of the bonnet. Reinstall the bonnet. Add a few screws to strengthen the bonnet - microwave connection. Make a template out of cardboard that is the size of your microwave top and press to indicate the bolt studs. Make holes, position the template and mark. Drill the holes, mount the microwave and use fender washers to help carry the wight.
It's been 3 - 4 years but I think the microwave weighs between 20 - 30 lbs and cost about $55.
Worked for me and might be a cheaper way for you.