There will not be tear in the slide seals .... Check the bottom of them, poke them to see if they are holding water ...... I hope ti came form that hole.
It IS possible to enclose the belly, it helps in cold climate to retain SOME ehat udner the belly but the furnace actively or passively (depends on the trailer) heats that area. It is nice to have warmish floors when you are camping in 10F degrees !