Not messy or super-strong tape, but something mellower and non-residue-leaving like “gaffers tape” used by roadies and theater folk.
Just a couple times around to keep the rolled up inner skirts tight together and from tweaking/separating much at all as the body moves. Might have kept me drier for my second swim in Class II+ whitewater - I was being very aggressive 
- after scrambling/twisting back onto my inflatable mid-river after the first swim.
try centering your neoprene tunnel…
of your spraydeck over the folded parts, that keeps me dry. Ironically, my last swim I didn’t do that and took on 5-6 ounces per leg after 3/4ths of a mile or so. Not bad, but had I fit the bundle under the tunnel I doubt I would have taken on a drop.
Augustus Dogmatycus
MMVI
Inflatable sometimes, no deck or skirt
Yes, I bet that would’ve been a big help if I was in my Diesel 65 hardshell, but this was on an open-decked WW IK, thus no waist tunnel.