I keep getting to the next plateau, then falling off again
I'm currently working on the close shots myself. Yes, parallax is a bu66ger. I use the lowest mounts I can get away with. I have just re-checked my aim points for 8 & 10 yards and found that I was slightly out - by half a md at 8 yards (most of my misses at Cambs last week were close shots). Why was it out? Probably because I hadn't properly sorted out my eye position when I originally set things up ... hurrying too much at the time. It helps to really spend loads of time when taking those close shots, moving your head backwards and forwards and checking, and checking again, and again, that you see the same amount of blackness all around the sight picture.
With regard to standers & kneelers, many shooters have their hamsters at a tilt (ooh, er, matron), so that the bit nearest their body is the full 150mm for standers but tapering towards the front, which aids rifle stability when kneeling and prone. Lack of stability is a by product of a deep hamster. I'm currently experimenting with a fully adjustable ACZ Ultra stock on my HFT500 which allows low-slung weights to be fitted, bringing the axis of rotation lower.