The main advantage of an early TMCC smoke function is the ability to turn it on and off via the remote. Lionel design of smoke is a little lacking hence the variations as time went on. MTH hit a home run right off the bat with PS-1 smoke, and patent their PS-2 version which is similar.
Lionel struggles with a single element to optimize it for conventional operation with a varying track voltage and load, against a Command environment with constant 18VAC on the track. Unfortunately the R2LC programming/hardware choices do not allow the system to respond properly depending on the voltage.
MTH Command engines on the other hand do, and smoke just as well at 11V as 18V.
So, you could convert to a constant voltage type smoke unit, or install and MTH PS-1 unit that handle voltage changes. Run the track power via a switch and the R2LC but use it to control a relay to turn on and off the power to a smoke unit.
Later Lionel went with a ACREG that controls smoke and uses a lower element resistance. This lessens any conventional operation issue. The ACREG is $30 and you change the element to 6 or 8 ohm depending on the ACREG picked. This would give you what you want. Or do the MTH one with relay.
You either optimize it for conventional and risk over heating in command, or leave it be for command and live with the poor conventional. You could drop the heat element resistance to say 20-24 ohm and gain some conventional improvement. G