Pause during warmup, BEFORE purge line?  

Pause during warmup, BEFORE purge line?

I'm printing something with ASA and I'm trying to streamline the enclosure warmup process. I have an enclosure heater that works well, but is not powerful enough to maintain my desired enclosure temp by itself. My strategy up to now is to just manually set the bed temperature, and continually check/change it before the safety timer shuts it down. It's been working pretty well, and I've seen a noticeable improvement in print quality when the enclosure is preheated for at least an hour, but it requires a lot of attention to keep refreshing the safety timer. 

I tried setting a pause in PrusaSlicer before the first layer but the problem is that it preheats, lays the purge line, then pauses and all the filament in the nozzle leaks out during the pause. This causes the skirt to come out all messed up.

I'm wondering if there's a way that I can manually adjust the G-Code to follow this series of events:

-Preheat Bed

-Pause/maintain temp for 60 minutes

-Preheat hotend after pause

-Continue with normal process (bed leveling, purge line, etc)

Any help or other suggestions would be greatly appreciated!