Suggestion to have an inline Mk 3 cockpit, somewhat resembling that of the Mk 2 inline cockpit, so we can have a little more freedom in designing our Mk 3 aircraft. The Mk 2 frame also has the nifty and ever useful Drone Core sliver, which the Mk 3 also does not have an equivilent.
As it currently stands, if you want to build a Mk 3 aircraft, the ONLY position your cockpit can really be is pretty much at the front of the craft, despite the small 1.25m mount point on the front, which usually ends up mounting either an air intake, or a dock port. The smaller aircraft airframes allow for the cockpit orprobe core, to be mounted physically anywhere on the plane front to back.
Now I'm sure I could hunt around and find a mod that contains a part that resembles what I'm looking for, but honestly an inline Mk 3 with Mk 3 mount points on both sides of the cockpit should be part of the base, vanilla game exactly like it's smaller brothers.