Curb Ramp?

[EM-0785]

Just found something that could be of interest to you. It plays on the theme of the curb bridging solutions per your initial post, yet seems to offer the added flexibility to manage variable sizes to an extent as you appear to need in your application. The example I saw online was called Curb Cushion (Catalog Item # 87763). Rather than having a fixed center depth and taper like several others, it features a thin 3/8" rubber ramping with drilled holes on either end of the 4' section that is intended to fasten wood underneath that bridges the trench/gap. I would assume you could use wood in width/depth/shape that meets your variable needs close enough, and attach it, then the ramp material would hold all in place and itself bridge the minor transitional tapers (you get the point!). Also may be simple custom units to then drop in place when needed. Best of luck whatever you determine. Brent