I've been shooting XPs for 40+ years. Tried about everything.
Harris' worked sort of OK, but needed something to rest the butt on for stability. On hard ground or wood/rocks the bipod gave a "whip" of the barrel & made shots go high.
I started using a backpack filled with a few soft pillows. That's worked great. Can rest it on the ground, hang it on a tree (with a screw in bow rest) & shoot off the top of it, plus you can carry all the goodies you need for your trip.
The newest rest is the BogPod PSR. It's fantastic for standing, sitting, kneeling. It's no longer made , BUT it's being made again on the Handgun Hunters International web site. I've tested the new model. It's as good as the original. I did a standing shot on a deer at 565 yards with the old model. It works.
As far as scopes on XPs, I'm still old school & use only handgun scopes (mostly Burris 3-12 BPlex), 2-6X, UltraDots (on revolvers). Used a friends XP with a rifle scope on a 719 yd. shot on a deer. Was OK, but I still stick to the handgun scopes. To each his own.