I use a rocket tipe semiSSTO. The key here is lifting the ship with traditional engines just enought to make the biggest karborundum engines have al TWR biger than 1, so I made a ship consisting in a central ship with the command, reaction wheels, EC, and all the needs for the vaccum inB9- HX structures with a HX docking port in the bottom; with 6 karborundum engines separated in 2 groups of 3 with the water needed for run, distanced from the center via tructural parts. And a ''service module'' withe de LOX tanks and their engines, the parachutes in high position (to land straight), the resource gatherers for refueling the ship, and the inflatable heat shiel maked huge via TweakScale. So you land with the service module, deatach the heat shield, deploy the chutes, then refuel and liftof with all the engines and when the LOX engines runs out deatach and reach orbit with bonfire engines and dock with the Eve Station and reatach another ''service module''. I know its huge and its not fully reusable but with the amount of karborundum you can take to orbit you will be served of karborundum for a very long time.
Sorry for the orthografi the spanish corrector mess it all. Any cuestions just write.