Dh plans to sand the rough edges and patch with a
fiberglass kit, do you think that will work? It seems to be caused by water damage, the camper had water damage elsewhere and the problem has been rectified.
If you can't tell from the pics, there is rot & separation where the belly pan & well meet to varying degrees.
roadside
curbside
There appears to have been a big patch here on the curbside and I have no idea what they patched it with.