Hi there,I'm no expert but can you drill a couple of small holes in each joint and hold the panels in place temporarily using self tapping screws until it's held by the first welds?
Or use ratchet straps to stop the ends of your clamps slipping - loop the strap to something above the repair area (maybe a bumper mount or something in the engine bay?
How snug does the patch panel have to fit?
I am planning on panelbonding and then screwing in tiny screw taps.
Thank you.