That's the problem with the VSR arm - the fulcrum isn't far enough away for it too be close enough to lay flat, and the surface isn't brilliant either because - unlike some other hop designs - it's not a two-part hop arm or even sloped to try and mitigate that issue a bit. I've known of people to build it up with a small amount material to get it flat, but then you're limited to a small range of weights. That's why it may be best to try the Biro mod first as it's basically reversible even if you glue it.
You're right in that the dead top centre mod was made to solve this issue. I've seen a couple of people do it, but never tried it myself. Seems like a bit of a nuclear option, but frankly if you're going to spend 4-5 hours constantly shimming the nub to get it at just the right angle then it does seem like a viable option.