Not specific to the P35, but years back we put up some lifeline lacing (not really netting) on a boat without a toerail by stretching a line along the stanchion bases and attaching the lacing to that. I imagine you could do the same with netting.
1984 Fast/Nicholson 345 "FastForward"
".. there is much you could do at sea with common sense.. and very little you could do without it.."
Capt G E Ericson (from "The Cruel Sea" by Nicholas Monsarrat)