I just burn prograde for the first burns, then use a node for the final burn. Apoapsis hight is varies, what is more important is the orbital period, which needs to be carefully watched so that you end up at periapsis again when it's time for the final burn. For each step, the focus is more on getting the burn done at the right point (within a few degrees) than achieving a certain apoapsis. It's about 200km from the observatory to Pluto. But as the roads aren't straight, (hilly terrain) but planets are placed where main roads intersect the orbit distances, it's longer to travel. We saw Neptune on the way in, so drove straight from Uranus to Pluto. Took more than an hour, not including the double back we needed to do to find it. Here is a touristy map I found: http://www.solarsystemdrive.com/pdf/map.pdf In KSP today, I began an Apollo style mission, trying to set it up with a rocket that runs similar. It blew up. Then it blew up. Then it wouldn't fly straight. Then it made it to orbit, and I noticed the fuel lines on my lander weren't connected, and my rover wasn't going to deploy properly. But, I fixed that, and now it is safely in LMO.