I had a PVC tripod-based rail pad in the May/June 2022 issue of
Sport Rocketry. If you're an NAR member you either should have it or can get it on the web site. The key part is a 2-inch side outlet elbow. When I wrote the article, Amazon didn't have them. They do right now (though you have to buy four):
https://www.amazon.com/FORMUFIT-F0023WE-WH-4-3-Way-Fitting-Furniture/dp/B00MNIZE0S/
Replace the 1/2 inch bolt and hose clamps that are used to hold the rail and use a drill chuck instead and it would easily handle a 1/4 inch rod. With two adjustable-length legs, it has some flexibility in setting the launch angle.
But since you're headed in a different direction, this is too late.
Add one of these for tilt:
https://www.amazon.com/VIELKNOV-Profile-Rotatable-Aluminum-Camcorder/dp/B0C9919XSP
A 1/4-20 bolt up through the middle of that tri-fitting goes into the bottom of the ball mount. A 1/4-20 stud on top is easy enough to connect to a variety of launching guides.
I just bought one of those and put it on my 3/4-inch-pipe-based tripod (which is a direct descendant of the "el cheapo" one on RocketReviews that is linked to above - but with screw-on legs, two of which act as a launch rod holder). I'm looking forward to seeing how much better that tripod head works than the two-eyebolt pivot described in
that writeup. But it's not strong enough to handle much of a 1/4 inch rod, which is what the OP asked for.
I absolutely agree with you on the advantage of a tripod over a 4-legged pad design.
I have two-eyebolt pivots on several of my personal pads including a 3-pad rack, and on both of the 5-pad club racks. It works reasonably well, though I've replaced the pivot thumbscrew/wing nut combo with a regular bolt with a plastic-insert anti-vibration lock nut on the other end, tightened enough to make it possible, but not easy, to tilt the rod. Much less fussy.
If that tripod head works well on the single pad, I will likely retrofit them to my 3-pad rack which I often use for small club launches.