RE: Airplane car carrier plans.
4x10 on a harbor freight frame. Honda Civic as tow vehicle. The trailer fully loaded is less than 500 lbs. Suspension is fairly stiff but none worse than my truck in the background (F350 dually, diesel, 4x4). I carry 2 giant scale or 3 or 4 .60 sized warbirds. Finished cost was about $650. Been using it about 6 years now.
Edwin
PS - Mileage drops to 27mpg from my 31mpg average.