i'm relativly adept at building the bodies of space planes in one go, (both in stock and far) and really only have to test the airframe itself once or twice but the part that takes me the longest and most testing is the landing gear, what i've noticed is that my planes seem to take off and land better with a narrower gear width, 1 wheel up front and two wheels in the back. what i'm curious about is why do i get better stability for having a narrower base? it makes almost no sense to me.
here's a pic of about how wide i have my wheels, any wide apart for the outside ones and i have uncontrolable wobbling on take off and landing is impossible, with this width i have nearly perfect take off but my landings require a parachute assist to slow me down fast enough to avoid crashing.
http://prntscr.com/ankk2r