Here is a video of a real CAT 319D climbing up some stepped platforms to unload crushed rock. Its an impressive piece of driving does anyone think they could do a radio controlled version of this video? 

If anyone does manage it post it on the RC Tractors Forum for us all to see and of course congratulate you on what would have to be an amazing RC excavator. I doubt mine would be able to do this as the boom judders too much so it would just shake itself off the platform but you never know I might figure it out eventually.