Amen to that; I have since found similar, although the actual rails were tight on ends, i did find some holes in the frame near the slide rail penetration that i had missed before. I have since filled those. Now also i found where mice were coming into the trailer box from the underfloor thru plumbing chase in the cabinet where pump is located. Factory had done nothing to seal this floor penetration. Plenty of room for mice and rats to enter there. Now filled with thick foam sealer, steel wool if you like. If the factory will not close up frame penetrations, vermin have a good place to camp out in the subfloor, and subsequently find a way through the floor. Should be a standard, yet inexpensive construction process. Do you hear me FR....