I built this a while back, when walkers just got a speed buff but after I made the M-14 Scarab
Turned out well, and it's pretty tough however since it utelises Plasmas and Missiles there is not a "low-energy" option. Missile Stinger for long range/AA action and secondary Plasma Ravager for close combat and splash damage against ground units. There are some hidden hovers inside, just in case your legs get shot off!
-Will post on the CRF upon commenter's request (just ask!)