18/54 is the sweet spot. As for bullet proofing it, by a flux. Actually the truck is pretty strong but it does have some weak points. Set the slipper on the loose side to save on drive shafts. Go with a single steering servo setup. Something like the hitech 5955 or 7955. Shim your diffs VERY,VERY well and it should last for awhile. RPM arms cause the stockers just break. The rear end tends to break off when crashing on it so you can use a pushrod as a support brace from a rear shock mount to the spot where the nitro pipe would screw into it. It helps a lot in this area. The stock wheels didn't last 5 runs without tearing apart. Aluminum skid plates cause the rears go out fairly quuick then you start to loose hinge pins. These are just some of the stuff I did and has helped. The best thing you could do is sign up to Traxxas Forums. They are dedicated sections in there about this one truck unlike here where it's mixed with mt's.
The erevo is a great truck and a blast to bash.
Terry