I know it would be easier to do it the suction cup way, but I agree w/Jon---  You really ought to set up there a minute, and figure out where you can mount something more permanent & substantial.

I thought my Outback had a great suction cup system.....then, one day, it let go, and busted the electronics.  Seems to me that temp. fluctuation makes is want to come loose.  Since then, I made a metal caddy, and the worries (and shelling out more money for electronics) are over.

Wishing you the best, and just trying to keep you from going through what I did.....because sooner or later, the suction cup systems WILL come loose.