Hoyt makes the Hard Lock rear mount that works for the RX series - in lieu of the screw you put the half moon against the string stop bar - works fine. But, they are not QD so I either use the Shrewd Hoyt Prevail Back Bar mount which is essentially the same but with a QD mount, or a Bee Stinger Elite which is a front mount hybrid.
The Hoyt is definitely more compact since it lacks a QD mount, which you might prefer. It changes the stab length. With the Hoyt on my RX3 and now RX4 an 8" rear worked ok also works with the B-Stinger since it's coming off the front, but the Shrewd or any other back mount with QD the 8" sticks out back too far... at least imo. So you would need say a 6" out back vs an 8 if going with it or any other typical rear mount with QD.
Hoyt
Shrewd
Bee Stinger
Here's my RX-4 with 10" and 8" bars with the Elite. TBH sometimes I think 8 is even too long here, I might change the rear to a 6. For some reason the Fuse bars are 1" longer than the Hoyt bars. It can be cumbersome at times. Sometimes I long for the simplicity of a single Simms SCoil or basic single front stab lol.