Its a great idea tho, and while its work, work, work, its possible to make. Like: wall sprite in vicinity of explosion: remove wall tile, replace with broken wall sprite. If GMs can remove stuff in RT without reloading the map, then definately should be done

As for ON TOPIC(sneak is fine imo):
I vote for B, new system. TB vs RT. Cant be balanced without ruining the other. If some day it would be possible, then there should be a seperate ruleset(mechanics) for TB and RT combat. All cities should have RT ruleset, PVE encounters(TB) should be left with current mechanics. If the player enters the encounter in RT mode, then naturally the RT ruleset would be applied.
Because....The game was made for TB. RT could be balanced but its still just aiming the same gun, the same dude, aiming for eyes, all the time. No time to think, no time to act. Its just chaos.
Like some RT rules which doesnt need much work and doesnt have new mechanics and doesnt help much, but at least would slow down the killing: HP doubled, heal doubled(may need restrictions), less crippling chances, and ffs less chance for an instakill. ...Just an example