You should be able to fit a miata on a single heavy duty ALUMA brand trailer, 3000lb axle and 77x170" bed. These only weigh in at 600-700lbs, you'd want to get one with brakes. A single axle you could have a better chance moving it by hand if needed.
Tow dolly is lighter, but you have to watch tail ground clearances and front ramp clearance. Used one for years and liked, but had to plan routes to not backup. Thats the downside of 4down and dolly-no backing attached.
Yes, you have to do the same with any trailer on ramp clearances but trailers you can use longer ramps if needed.
Appears you can get a hitch for a miata, as long as you were not towing a loaded trailer, it could move a trailer around a campground.
2006 Gulfstream Ultra 6331
33' Super C
8.1L V8 Gas