Best way to feed in composite or s-video luma to a B&W Tube set?

[VintagePC]

I've been looking for info on this and wondered if anyone had some good resources for a way to add support for composite (or S-V luma) to a B&W tube set (specifically, my fleetwood I'm restoring in another thread here).

I've found a few things but they seem to be rather outdated and/or the links/reference material no longer work, so I was hoping someone here might have some thoughts.

I gather direct circuit mods aren't easily done without additional SS circuitry owing to the different nature and impedance of tube drive signals.

I do see cheap RF modulators littered all over fleabay, and even B-Ts can be had for $40 or so including shipping - except the BTs aready require a 75 ohm coax signal in.

Any comments/thoughts on cheap RF modulators and how capable they are - or is it better to make a small drop-in SS module to amplify the signal?

I would assume the signal level on the cheap-o mods isn't high enough to be able to transmit wirelessly, unlike what I've seen some folks here do with the B-Ts.