Hello,
I too have a Remington XP-100 in .221 Fireball. I have a red dot sight on it. I tend to hold it like a rifle with my left hand griping the forend. I have a laminated Fagen stock on it to replace the factory plastic one. I once saw a "Stick" type support made by MTM who also makes plastic cases. It looked somewhat like a walking cane and had a little support that moved up and down. You put the bottom on the ground and held it in your left hand while supporting the gun on the support with your right hand. For low vegetation there are small biopods that attach to the barrel or stock.
Bob