I did the same thing in my garage floor , except I welded the receiver hitch to a 18x18 plate ,
aaaRGH so simple! i just spent the night rigging up a hand crank winch, bolting stuff to the floor. Kicker is, I was planning to add e-track anyways. Wish I'd though of this first. have you pulled a car in using this method? i would think you would have to reinforce the walls first.... thankfully I'm just hauling in 500-600 lb pcs of equipment.Just put a chain/strap anchored to the forward most slot in the E-track. Hook the winch in the middle and pull.
If I saw wrong trailer and attributed to the OP - you can do the same with the forward most D-rings that are in most trailers I have seen.
