Firstly, welcome to the forum.
Developing 4x5” film is, as you are finding out, varied and interesting. I have developed 4x5” film via various methods, notably using a Jobo CPE2 rotary processor, which is good but expensive and not what you need at this stage of your 4x5” photography career. I have been using my Jobo to rotary process all of my film, including 4x5” for close to 30 years
I have seen and handled the MOD54 insert for the Paterson 3 reel tank, looked at the clip from the inventor(?). If you already had the correct Paterson tank, then I think that could be a reasonable way to go. It requires 1 litre of developing solution.
Then there is the SP-445 tank as shown in the clip in this thread. The actual film holders shown in the clip indicate that this is the first version of this unit. I have this same unit; I was part of the kickstarter group. I am more than pleased with it. It requires (in my case) 465ml of solution.
Later models have had their film holders modified, for possibly two reasons. One to enable one to remove the film more easily after developing, two to eliminate possible marking on the back of films.
I never had any issues with removing the film after developing, I simply place the loaded film holder onto a tray of water (I use an 8x10” paper tray) and the film virtually slides out of the holder by itself. As for marks on the rear of the film, I haven’t had any, I’ve put Foma, Ilford and Bergger films through my SP-445 unit with nary a scratch.
I do though, use a wetting agent bath at the end by using a 5x7” tray with the wetting solution in that and place each sheet in individually and then hang to dry.
After using my Jobo rotary processor for developing all of my films, colour and B&W for close to 30 years, 135, 120 and 4x5” sheet film. I continue to use it for 135, 120, but have switched to the SP-445 for 4x5” film since obtaining that unit.
It is really easy to use, able to be carried on trips for on location developing; which was my original reason for procuring this tank. It gives me a very fine and even development over the entire sheet of film; this is all I require of any developing tank.
Mick.