How far are you going OCD? There are the flat forends and the $1K rests.
There are the myriad run-out gauges and, of course, the Wilson seaters because there's no way you'll trust a mere press to seat your bullets when the only right way to do it is by hand, so you can personally feel every micrometer of progress of the bullet into the case.
There are the custom bullets that you'll use until you decide you can swage better ones, yourself.
Somewhere along the way you put your rifle into a real, long-range benchrest stock.
After that you'll discover barrel tuners and you'll drive yourself nuts with their infinite adjustability.
If you really go off the deep end, you start booking time in testing tunnels, measuring groups to 3 decimal places, and not being satisfied until you consistently shoot 100-yard tunnel groups with c-t-c measurements "in the zeroes" (0.099" or less).
Eventually, you'll start looking at ways to just brute-force all the variable out of your shooting, so you'll find yourself looking at rifles like this
while the voice in your head says "All I have to do is move a few financial obligations around..." and you actually begin to believe your thought processes are still rational.
I've known people who were obsessed. It can get ugly.
So just how OCD do you want to go in the pursuit of small groups?
Ben
PS - The above is just for fun. I think you're trying to find best results with a particular rifle, right?
I'm gonna do every one of the things you named except for the expensive stuff
