The freeman tray is wider than the brushy mountain board .Brushy Mountain's mite-board can slide in from front or back.
If a tray were same dimension it could slide -- big IF.
I'll check my Freeman beetle trap tray tomorrow but I think it is wider than Brushy mite-board.
I think you could probably make them yourself. You don't really need skill so it would be definitely in your wheel house.Which manufacturers make SBB with front loading trays in 8 frame width?