That's true that the reverse is located a bit further away because you need an 8-way sticks for Robtron, Bubbles, and Splat!
What I did on mine to compensate was use the 3 1/2" Wico shafts (instead of the 4" Robotron ones) and didn't route the underside of the control panel. That puts your hand closer to the control panel and makes the Reverse button very easy to hit with your thumb while still keeping the balltop in your hand. That's about the best you can do if you need to use an 8-way stick with Defender/Stargate.