For groundhogs I use cheap arrows with field tips that produce a reasonable group at 20 yards. I look for fresh holes, toss dirt they pushed out to cover the hole. My folding chair is placed 20 yards away on any little hill or elevation to get a downward shot. I set the xbow in my Bog Death Grip aimed as close as possible. If they are coming out it usually takes about 20 minutes for a head and shoulders to poke out. They drop with almost any movement so having the xbow basically set close to position requires limited movement. I use my RDX 400 and would not use the TP 505 or a HS xbow. A good/lucky shot kills or at least pins them. I carry a .22 pistol to put any wounded ones down quickly. GH tournaments usually will not accept bullet holes, but I'm not excited to stick my foot on one, they are pretty impressive up close.
Squirrels would be tough and I'd never shoot skyward like you might with a flu-flu arrow from a bow. Rabbits might be OK with a field point as they will frequently stop after running a short distance, but its usually in a brushy/weedy spot.