I've a thread about this on the BBS.
I mention on there that I'd seen posts of yours in the past ( think it was when I was reading about your stock projects ) where you'd put weight in the butt.
I've just taken the Wegu buttpad off and refitted the simple alloy plate that I used for HFT. That loses about 3/4 inch of the lop ( which suits me ) and brings the whole gun backwards and moves that front hand forward. I've also just lowered the palm rest. It feels quite good now sitting. Kneeling and standing are fine.
I reckon the scope is going to have to go up a tad on a riser. I reckon with a wee bit of weight as you suggest at the rear and it's going to be pretty good.