I just realized that I made a mistake in my filter circuit: I used a 330Ω resistor where I should have used a 33Ω one. That means my cutoff frequency is roughly 500 KHz instead of 5 MHz as I had intended. It still works, though it might work better with the correct component. I plan on finding out, and I will document the process as much as is reasonable.

I plan on adding multiple low-pass and band-pass filters that can be switched in and out of the circuit as needed. I get the feeling that this is going to involve a fair amount of calculating, testing, and hair-pulling.