I set my throttle to number pad keys, plus and minus. It resets everytime back to left Shift and Ctrl. So every time you have to open the settings, close the settings then it works.
I have made an SSTO an named it TechnoPlane. In honor of the late Technoblade. But here is a video I made. I go out to Minmus deploy a small relay. Return to Kerbal and land at the KSC. I have visual mods and use Trajectories.
That was a fun and tricky challenge. Will be editing and putting out a little video soon. Here is my submission: https://imgur.com/a/zUmvpFz (453 m/s left in orbit)