Shawn, if you make a sifter out of 2X6s and 1/4" hardware cloth you can sift them out of the sand very quickly and easily over a wheel barrow. I made a new 2x3-foot frame that sits across the sides of a contractor-grade barrow and I just park the whole thing under the trap when I dump it (by removing the front a little bit at a time).
I'm not sure why you used the Lexan, looks like it tore up the panel behind it pretty badly as the shards cut through it.
All you really need in the front is some sort of wooden panel (osb, plywood, etc.) and either the mudflap like you had or felt paper, or even asphalt shingles behind the wood to act as a stopleak, and a front layer to pin the targets to. I use 1/2" asphalt sheathing on the fronts of mine, held on with a few screws around the edges.
Anyway, for general trapping (not forensics) a little sand does a lot of stopping, prevents fragmentation, and it is super-easy to sift the boolits out. Only downside is weight, but then again it doesn't take much thickness to work well.
Gear