Also known as Nightmare Beach!
I can't recall any of it taking place on the beach, so not the most appropriate title
edit - oh yeah the "t+a" sections do
For similar hilarity I recommend checking out Hitcher in the Dark (1989). I believe they use the same RV seen in Troll 2 and Welcome to Spring Break, though my mind's a bit hazy on WTSP because its been a while since I've seen it.
will do, it's another Umberto Lenzi's movie. Just watched the trailer and I think I've possibly seen it before, but would've been years ago if so...