How do you plan to use it? I full-timed in mine for a few years while saving up to buy my DP. The air conditioning and gas furnace is adequate. There's a heater option for my air conditioning unit that I've thought about but shrug off in favor of the space heater I've already got. I didn't think much of the gas stove. I used my microwave and an induction hotplate for most of my cooking. It's a bit cramped for any real meal prep.
They can be nice trailers if you pay a little attention to them. The awful interior lighting was a priority for me. Also, the fridge was bad when I got mine so I pried it out and converted the space to a pantry/coffee station. Gotta have my morning latte and it's gotta be convenient. The dead fridge was so tiny it was about useless for FT, so I think I made a better use of the space. I figure I can get one of those plug-in roll-around tailgating coolers if I need a fridge on the road. When at home base I have a residential fridge outside the front door under the awning.
Here's the top 10 list for my '93 20' Layton. These are in no particular order and may not apply to yours. Some are pre-emptive or upgrades. Others were necessary to make it livable.
10) Propane cooktop and a convection/microwave oven.
9) more house batteries
8) more/larger propane containers
7) a meaningful solar panel
6) winter window coverings/better door insulation.
5) redo the roof
4) improve outside lighting
3) LED/improve/add lighting throughout
2) add outlets
1) redo plumbing fixtures
Time flies like an arrow. Fruit flies like a banana.
TARDIS Project 2001 Mountain Aire DP40' 330CAT