get thumper neutered.
i had my bunny spayed, even though she was an only rabbit here, cuz my vet said it would help prevent female sort of cancers.
maybe neutering thumper will help him not get male sorts of cancers AND maybe it will reduce his humping desire somewhat. i dunno. ask your veterinarian.
if not, i still holler for first pick of any freaky litter that may <strike>probably won't</strike> occur...