Hi simplecarnival,
sws' extension plug-in now comes with his marker actions included:
SWS Extension
After installing it to REAPER/plugins folder you'll be able to build these macro (Custom Actions):
For Recording (pseudo-preroll), You'd need to navigate first to your desired location and place marker #10 and name it: !1013. After that run this macro:
*Add/move marker 10 to play/edit cursor position
*Move cursor back one measure
*Move cursor back one measure
*SWS: Enable marker actions
*Transport: Play
This macro will insert/move a marker at edit cursor position that will engage recording after being crossed.
To Stop Recording, you need to build this other macro:
*SWS: Disable marker actions
*Transport: Stop
NOTE: you could mix both macros using meta-action "prompt to continue" between first macro final and second macro so you'd only need to press "Enter" when you want to stop recording.
Warning: marker actions have some sort of random delay (30ms or so) from the very moment play cursor crosses the marker. Please, always try to place your marker 10 about 50 ms before your desired location to avoid later issues.
Let me know if it works for you