:welcome:
If you don't already have the XM TailCap, you may like to consider getting either the XM00 or UM00 TailCaps. The "00" indicates that they don't have any remote switch (which is normally the standard STxx). Since you want to use the SRxx remote switch you may not need to get a 'complete' XM system such as the XM07 (which comes with the ST07).
The UM switch is one without the secondary clickie switch - it's for the remote switch only.