How to protect yourself for PP Pickups?

Is there any solution to this option? I run store, now with over 300 items on board. I have in every listing, stating that pickup is cash, PP is not accepted. I would much rather the money going into my PP account really, saves me going to the bank....I got burnt when I first started by this and lost the $$$ from the sale, thanks to our friends.

So. Could I write up a pick up form for the customer to sign when they pickup the goods? Or how do others do it to protect themsleves?

Pickups equate to around only 10% of my revenue, so if I refuse pickups, I may lose this revenue.

Thanks.