The overall length of a trailer is NOT the critical factor in the stability of a trailer!
There are several factors:
Distance from the hitch pivot point to the axle.
Tire track (or center to center distance the wheels?
Spring center to center distance.
Wheel height (or distance from the ground to the axle center)
Just look at the difference between a motorboat trailer and one for a sailboat.
The motorboat trailer has the axle very close to the motor.
A sailboat (especially a keelboat) has the axle near the center of the boat.
That's due to the for aft COG.
Same goes for height of the COG, the higher the wider the track is needed. (The same trailer with a load of stone compared to carrying a raised Jeep. The stone is stable due to COG)
As far as 'backability', there are two major distance factors:
one-being hitch to trailer axle and the other is the distance from the tow vehicle axle to the hitch. (Try backing up a 5th wheel or a 48" supertruss)
Most comercially made trailers have these factors worked out for "standard" loads, but is your load what the manufacturer was thinking about. Putting a heavy quad behind the axle without much up front is not what they were thinking of.
You should put almost as thought in getting a trailer as a TC, without the wife factor
