Making Foldable Beds more comfortable in Hybrid Trailers

Get whatever thickness memory foam you think you will like, cut it to size, and then cut it in half. Make (or get someone to make) a fitted cover for each one, out of quilted fabric like a mattress pad. Personally I wouldn't bother trying to stick them together with Velcro, unless they separate so much it's annoying.

Get a bike rack for your bikes, and much of your problem is solved.