Try a baggie tie (wire kind) to tie your motor clip down.

What I did was thread it through one of the holes in the back, making sure I left some hanging out.

I then straightened out the clippy part of the motor clip.

After that, I looped the baggie tie over the clippy part and when it was properly tight for the motor to work, wrapped the end around the part hanging out from before.
It may be possible to get the body over the clippy part, i don't know, as bodies vary.

This ain't the kind of setup you'll get many disassemblies out of. setting up and leaving it would be the thing to shoot for here, unless you don't mind replacing the baggie tie.

It's crude but it only requires a baggie tie (or even a piece of cat wire, come to think of it) you get the idea.