Technically you could add up all of the current draw from your accessories and see if it exceeds the output of the regulator (and who better than Chy to trust on this?)...or...you could switch off the running lights when you plug in your warmers and make it an either/or choice, lights or warmth.
This Triumph Rat mod to charging system was on my list of this to consider as a future "improvement".

A positive attitude may not solve all your problems, but it will annoy enough people to make it worth the effort. Herm Albright (1876 - 1944)