Yes exactly what I was going to suggest and what I did with my Ram 60CX cradle on the Mirage 2.
I have two alu. spacers (and longer bolts) giving me the needed clearance to push the locking tab in to remove the 60CX. I would recommend something solid as opposed to rubber though (unless it's really hard) otherwise it may move to much while trying to unlock it. Don't know how much space you need but a trip the hardware store should come up with something.
I don't have any pics specific to my set-up though sorry!
Moto Overland [MOD] -Skid Plates, Top racks, Tool Boxes etc for Adventure bikes