Question about tailgate strength/spare tire

[goser]

I've been looking at various options on relocating my spare, and after being snookered at almost every turn I've decided that the best, most cost efficient option would be to bolt a spare tire mount to the tailgate. Something like the kind that attaches to a RV bumper... (see http://static.howstuffworks.com/gif/...re-mount-4.jpg) Looking inside the tailgate there seems to be some sheet metal 'framing'; I'm just wondering if anyone has done something similar or has any input on the structural feaseablility of this before I start drilling holes in my baby.