Matt,
The subject of SECs and BECs reminded me of an Astro Flite plane I had way back in the "E days (Early not electric). I don't remember the name of the plane but it was a 3 channel high wing with an Astro 05 ferrite motor in it without throttle.
I rigged an On/Off switch and flew it that way until a friend gave me a Slot Car throttle controller from which we removed the wire-wound reostat and mated it to a servo for a throttle controller. We lengthened the servo control arm and rigged it as a a wiper with a contact point on the end. It moved up and down the length of the reostat in reponse to TX throttle stick input. The wiper was in turn wired to the motor battery pack. The power pack had a separate On/Off switch. The plane toted two battery packs around but it was no problem.
With the throttle stick at full down, I'd turn on both battery packs, then move the stick up a little at which point the prop would start ticking over. Moving the stick slowly upwards the plane would taxi out and then with more power take off.
My homemade throttle worked like a charm and gave me lots of extended flight times on during many, many late afternoon flights.
It was fun doing-it-myself, but I don't want to do it again, and thanks to today's SECs and BECs I don't have to. These are now the good old days of flying for sure! Grampaw