I also use tissue but don't soak in PVA/water until after it is rolled otherwise it can end up a stiky mess.
I roll the bed rolls by folding the edges inside so that the completed roll does not have a zillion edges poking out. I then tie the roll with cotton thread to pull the roll into that puckered shape you usually see. Leave a long piece of thread so you can tie it to an old paint brush or piece of wire that fits across the top of the jar with the PVA/water mix. Then you can dangle the roll in the PVA/water mix for a while.
Then take it out, snip the thread and press onto the model as above, making sure any tie down belts etc are behind the roll so that you can bend these around and connect them later.