Thanks to all for the replies.
@320 - yes the Mcrews fixing was an inspiration, the U-shaped mini clamps seemed an idea as I can remove them with a screwdriver.
@Various- tape and velcro are a possibility but I need to be sure I can remove the tape residue with no paint loss, the paint on the rear "bumper" (plastic) is not all that great, it came off the inside - having a go at Toyota about that one.
I'm also looking at this
metro build thread, that looks cool too.
Right then, materials gathering is going to commence, and I will add to my thread.
Any other ideas welcome though.