Enclosed trailer.

[Wulf202]

On a small trailer the expense of aluminum isn't worth the small savings.
If they salt the roads where you go it will have an effect on the frame.
Ramp is better. Bring extra motorcycle stands or get the cable kit and use it as a deck. A not so muddy space is premium.
Skin doesn't matter. Rivets are leak points for water and air.
Walk on decks are not usually built well, also don't risk your waterproofing like that.
Try to match the wheel width of your tow vehicle, it will whip badly in ruts if you don't. Also look at your mirror width and don't get a trailer wider than that
I advise to get a happijack bed set. That's the brand name of bunk beds on tracks that go up in rvs to clear the toy area.

As dfbrews said but make sure that door has rv handles. Get a window on the opposite side for egress and cross flow. Put in a good vent fan not the junk cheap ones. Get a fan cover. Find a low profile chalk mount, preferably flush. Add 2 Co/fire detectors. Bring a fire extinguisher mounted. Insulate the thing. Get one with brakes. Ditch the Chinese tires that will undoubtedly come with it and buy Goodyear. Get a spare and a bottle jack onboard along with a wrench.Get ez lube hubs. Electric tounge Jack's are usually worth it. Get rear stabilizers so you can load and unload unhitched. Try to include things that will save you time and frustration

I would spring for extra head height so you can insulate. Also v nose does help some with towing and gives you room to do a built in cabinet for misc gear.