I sent a scouting mission and eventually I wanna put a base on Urlum's small moon Priax near one of the poles. Although it looks like a regular fuel tank slapped on the front with a chemical engine, it's actually a 
The main propulsion is the NSW engine from the Far Future Technologies mod, and the whole ship has well over 500k dV which is great for zipping around the Kerbol system. In another ksp game I did a few years ago I used basically this same ship design to visit every body in the Minor Planets Expansion mod.