Speaking of JSONs, I made just a couple of iterative edits that has made my second playthrough pleasantly more difficult.
I changed spotting distance from 300 to 450.
Changed sensor distance from 400 to 750.
I edited down PPC heat from 40 to 33 (still one point higher than TT to account for EMP effects on target)
I edited down LL heat from 30 to 27 (one point higher to account for laser accuracy bonus)
The net effect of the sensor changes has made the early game far more dangerous, because all those light armor lances just hammer you with LRMs and AC fire from about 400 meters. Really cool and tense battles have developed.
The net effect of the heat changes have made the Panther, Vindy, and Griffin more viable in my lances, because they can fire for an additional round or two before needing to cool off. Also, the OPFOR fires more often when they have PPC's and LLs, so more damage is flying around in general.
I've never modded a game before, but I have to say, really enjoying fiddling with BattleTech now that I've played it through once the way the developers intended.