can i- should i- prune my watermelon vines? [View all]

they are completely insane, taking over the whole block! the thing is, i know that melons starting now will not have time to grow and ripen. i have a couple beautiful big ones, a few small ones, and, i assume, a few hidden ones. sure they will be delish, but that is a lot of space. not that they are hurting anything, but...
i just am thinking that if i pinched back the tips on the vines, they will concentrate on ripening up what is already there.
good idea? or bad idea?