Bikes/quads are fairly easy - get as many of these as you need (4 per quad, 2 will wok on a motorcycle) and pull down against the suspension. 6 ft. Cam Buckle Tie Downs, Set of Two
In my cargo trailer I too have etrac (harbor freight has some, grainger other bits). They sell eTrac rings Search results for: 'etrac ring'
that you can place or remove as needed. I put track on teh walls as my trailerhas big rings in the floor for quads. Used self tapping fasteners and attached it to the 'studs' (frame?).
they also sell 'brackets' that clip into etrack that fit a 2x4 - handy to make a shelf or brace across as a cargo hold, or what I did was put on 1' long 2x4 and made a shelf that can be removed.