I made this for my 2010 Rav4, but I assume it will work for all 2006-2012 Rav4s since they have the same body style.
I wanted to be able to stand up the bike inside (with the front wheel removed) so that I didn't have to worry about the possible damage or security problems of an exterior rack, but still have enough room left inside for something besides the bike. The Rav4 is a pretty small vehicle - what allows this to work is that the spare tire is mounted on the outside of the tailgate, which provides a cargo area under the rear floor, giving some extra interior height. It won't work in a 2013 Rav4, or a Forester.
The parts are:
Visible wood piece that rests on the fender wells.
Wooden stiffener that screws on underneath the visible piece.
2 front fork truck bed mounts.
I used a "Delta Fork Block Pickup Bed Mount":
2 small barrel bolt latches
Screws and glue.
Step 1: What it will look like
The rack attaches by sliding the barrel bolts into 2 holes drilled into the plastic interior panels (one on each side); the holes are underneath the carpeted cargo deck lid, so they don't show. In fact, when you're not transporting a bike, the rack doesn't even have to be removed before putting the deck lid back in place.
If you're much taller than 5'8" the saddle will hit the ceiling, so you'll need a more complicated stepped structure that will allow the fork mounts to be positioned a few inches lower; but you can only go down a short way before the chain wheel will start to rest on the floor.