Alright, quick morning update. Much better success this morning, thanks to my non-tired brain and some finer tuning. Turns out I had the capacitor way off tuning-wise. And, I think the comments above about this capacitor being a little too large in range are probably true. Every 1/8-turn moves me a good 100KHz or so, if not more, so while the stepper motor I'm planning on adding should be alright, I'll probably look at investing in a gearbox reduction of some kind just to make things a little more precise. When I have some more time this afternoon, I'll actually set it up on the balcony and try some HF. These initial results are promising though! Definitely happy that my design isn't a total flop.