Alright, found an actual 3-turner now, perhaps lightly inspired in some ways by things discussed with Senator. It's different in a few pretty relevant ways from his own solution though, so I'm happy enough with it. It's not really the solution I was initially going for, but that one might straight up be impossible, haven't found a way to get it to work yet. And certainly that one would be less repeatable, what with probably having to do the jump into the dyna explosion and such. So this is cleaner, plus it makes use of the thing that Abegod said about weapons dealing damage to both worms and terrain...
Oh yeah also, I did eventually watch your almost solution, Zalo. You're a crazy f@#!er, that's not repeatable at all! But really nice idea anyway, the way you found the path into the tunnel.