I could use some help modding RTX 3080 FTW3

Hello.
I switched from GTX1080 to RTX3080, and this one is EVGA 10G-P5-3898-KL. I used extra fans under the GTX, so I decided to remove the cover of RTX and let this sweet airflow do its thing.
I kept the card's fan and the frame it sits on. It is joined to a heatsink, and all this is held by one screw and a thermal pad. On the other side of the pump, another heatsink piece sticks to the card on the thermal pad only.
The overall gain in temperatures doesn't justify warranty void, so no joy. I am ill-equipped and unprepared, so I have a couple of general questions, like - what to do, what to do? And few more specific ones.
Would it be a good idea to remove a fan and the piece of steel it is mounted on? I haven't tried to start it with a fan unplugged, but I assume it won't mind; LEDs unplugged without hassle. I am not sure if this fan does any cooling right now, same for the metal bit.
Can I get better heatsinks? Unfortunately, I have no tools to cut to size and drill holes for mounting etc. Perhaps you know where to get good size pieces? The on-card heatsink fins are oriented along with the card. If I had one with fins across the card, I could at least tight it up with cable tights. That would be an improvement. I've looked a little after heatsinks, and the deepest I've found was 36mm. These I have, are ~20mm in depth. The last thing about heatsinks, bases aren't flat. It is like a 1mm difference in thickness, so I could level this up with different thickness thermal pads. Am I right?
What to do with a backplate? Right now, it holds on one screw, which holds the radiator and the fan thing, plus cable tights on the corners. Can I do better than that? Should I look after nuts for these tiny screws?

The 3080 heatsink design was optimal and you should put it back if it is not already but it sounds like you have a thickness issue? The pads are too thick? I smash them under a hockey puck or something flat to make them the thickness I need.

It also sounds like you are missing screws?

I would use a good thermal paste on the GPU itself and pads on the memory.

I hope I am not trying to go beyond the extreme here.
I know I don't need a better radiator. All I need is one of these air-conditioned rooms where's 21C ambient temperature. Once I'll get optimal ready, I promise I will put the card back the way it was out of the box.
My issue with thickness is its relationship with heat transfer. This is the best piece of metal I've found so far. I could cut 2-3 fins wide bit, and a piece like this would cover the MOSFET strip through a sub-millimetre thermal pad. Same for inductors. Does reducing thermal pad thickness from 3mm to 1mm isn't worth doing?

I will come back to screws once I have heat sinks sorted out.

This is a hybrid card. An AIO covers GPU and memory. https://m.media-amazon.com/images/I/...AC_SL1100_.jpg

Try to find something in copper, nickel plated is fine.

You can buy the correct thickness or you can modify yours, just make sure there is no cracks or uncovered parts of the die. You could even try tim if they already touch.

Thinner pad is better if it fits correctly

EVGA does a great job with their coolers, especially the FTW3 and Hybrid series. I see no reason for you to even try what you are attempting.

Getting even better airflow into and out of your case and setting that up optimally is going to net you more than trying better what EVGA has already done.

Re-pasting the GPU with a known paste great for GPUs and better thermal pads are only going to gain you a couple of C too. Like I said, EVGA's cooling for the FTW3 and above series is spectacular IMO.