Man, that frame looks really great!

I know your just mocking it up, but you'll want to lower it, a lot. Try and get the links parallel to the ground, or as close as you can. This will keep the center of gravity low and make the rig much more stable. Keeep the battery as low as you can get it. Heck, strap it to the upper links if you can.

Also, make sure you have a nice smooth skidplate on the bottom of the chassis. It will let you slide over rocks instead of getting hung up on them. I use sheet metal, but I've even seen people use those thin cutting board sheets. Makes it nice and slick to slide right over the rocks!

Post more pics as you get more done!