Why not just get on and do it.
Use c152.
Use card board tube with end caps , the sort you use for posting maps.
Tie the tube to a piece of string you can keep hold of.
When at height remove end caps.
Be preparred for blow back in the cockpit.
I'm sure i had a piece of bone in my eye.
Last one i did the deceased wife reconned parts of her husband ended up, in the carpet, down the sink and up the Hoover.