I've developed a viable route from the end of Zone 4 (just after Marathon Man) to the Final Zone, without using the space mech suit.

This is not yet useful in a run, as we already have the space mech suit. HOWEVER, my goal is to develop a route from Zone 2 (just before Death Machine EX) to Zone 6 (at the top left of the map). Once this is done, it will be viable to completely skip Zone 5, Genbu, and the Vehicle Key entirely, and we will be able to navigate through all the space segments without the mech suit.

Anyway, here's the route!