riverman wrote:

I was thinking that since, as a kayaker, I have a tight fitting neoprene
seal (in the form of a spraydeck) around my waste, that should keep the
water out of the lower part of my suit.

Yep, that should do it. Good thing, too. As a rafter, I never appreciated
the importance of having some sort of waistband; but now that I know the
impact of having a leak in a drysuit, I'd strongly encourage any rafters who
wear drysuits to also include a wading belt to seal off the lower half.

A dry suit with a double tunnel would accomplish the same thing. It's
like wearing a cummerbund.