I hunt coyotes with the SPs most of the winter months. Here is the system i use--
I call, spot and stalk, and walk many miles in the country i hunt so i need something extremely portable. Typically i just use a tall Harris bipod and improvise a rear rest with my pack for prone position long-range. All of my shooting when calling is from the Harris at an extended position sitting. But to shoot these SPs accurately from the sit u need a good backrest. Plus u have to be able to take it with u in the field. The best i've ever found is a soft-sided stadium seat that u can find at the K/Wal-Marts. They often carry a "heated seat", which is just a little thicker closed-cell foam in the butt part. The 1st thing i do is shorten the female part of the side straps, so it's attached as close to the seat itself as possible (the seat doesn't work well without this little customizing). This way it gives me excellent back support. The next thing i do is get a burlap bag and cut holes in it for all the attachments, then sew it back up once the seat is inserted in it--usually fits perfectly. This helps with camo, IMO. Now attach an aditional snap at the ends of the side straps so it can be carried around your waist hands-free. Now practice the system from the sitting position with pistol grip behind your bent knees forced against each other using the tall Harris at the extended position. This is an extremely steady position to shoot from, believe me, u'll be surpirsed what can be done from this position.
I killed this coyote using that system--
Another time i shot at a dirt clod on the side of a stream bank @ 1000 yds. and missed left 4" using the same gun noted in the reference above.