Prelude 2.0
Just keep in mind that a rear bag system like you are asking about would not be legal in the rimfire 3-Gun events, but would be fine for any of the Unlimited events such as any of the ARA events, as well as for RBA & IR 50/50 Unlimited.
Another rear rest system similar to what you are asking about was made by Art Cocchia of Time Precision for a while many years ago. I don't know if Art's still offering them, but they were nice.
Good luck,
Dave