Alternative would be a different track layout. Universal opened Volcano Bay last year with an aqua coaster where it's pretty much impossible for the raft to come up because it, surprise, uses upstops to prevent it from going airborne.
The difference, of course, is that the netting in the image on that page pretty obviously isn't meant to catch people. It's more likely there to keep birds out or to keep somebody's phone or hat from shooting across the park at high speeds, or just to keep idiots from intentionally climbing out of the tube while it's elevated.
It is pretty normal to have netting underneath things like inverted rollercoasters, since people inevitably drop things... Not netting where people could collide with it.
Whats interesting, and where they probably for the idea for the netting (they have one in the park): https://www.whitewaterwest.com/products/master-blaster/