I saw a great bike rack on a party barge last year that. It was basically just a horizontal pole (they had several of these racks, actually) with a brace for support and several hooks along it's length. The pole was up high enough that you could hang bikes vertically by their wheels, and the hooks were spaced out enough for the handlebars. Seemed like a very simple design that worked well and allowed you to get the bikes off easily, and it any order.

Do I understand you correctly; you are wanting to know how to buikld a bicycle rack onto a trailer?

There are three basic ways that I know of;

1) Mount a standard motor vehicle towball styler bicycle rack somehow onto the draw bars. could be as basic as bolting it to a square pipe that is u-bolted around the drawbar arms (assming triangular drawbars. Very common in Australia for RV'ers, caravaners, etc who carry bicycles.

2) If the trailer has a cage/frame, mount a similar bicycle rack to the cage on the front, or either sides (over wheel arches?-watch clearances).

3) If the trailer has a high cage or frame (build one), the method I used for commecial trip customers was to run two parrallel pipes wither side to side or back to front and suspend the bicycles from the pipes. I made up 3' lengths of rope with spliced eyes for this purpose. Two ropes per bicycle. Cover the bicycle with wheat bags, or simlar slit down one side, or a "saddle cloth" of old carpet/blankets, etc. This is probably just a variation of what you were proposing.

In all cases, usually easier to remove pedals (less scratching, damage to other bikes, etc)