I reckon you’ll have to sort out what works for you.
We use a raft to raft out after our wilderness fishing trips in NZ, but haven’t needed ,or wished, to fish whilst rafting.
I’d probably just put my rod on the spray deck, and have a paddle leash, and hope like hell there was no white water to negotiate whilst trying to hold all this together! I’d also make sure you don’t fish a sinking tip, or beaded nymphs - the former likely to hook you on the backcast, and the latter more likely to hook you on the forward cast.
Ultimately I think I’d rather fish from the bank, and use the raft for travel.