Deployed the next stage into a 70km apogee trajectory with enough fuel to get itself into orbit and back.

Had three swivel engines and six reliant engines. Boosted back from a 45 degree angle trajectory with 70km apogee, using Trajectories for the burn. Made a quicksave and was able to land in 2-3 tries. Lit 5 engines for landing, then 3, then just swayed down to land by hand lol.

But I have a question:

Obviously I can't control the next stage and this one at the same time, so this has no use. But if someone can give me an approachable resource to kOS, I think I will try automating this so that I can play with the next stage and know that the first has made it's way back home. Actually is that even possible? Does the game even let you do that?