First this is the soldering you hav to do to turn the TC-420 into a 5V PWM signal (only needed 4 outputs w/ this one).
If you don't want to do that AND exceed the power threshold you just need larger MOSFETS..
See top.. Now this was done not to increase power handling but to "invert" the ground since the TC-420 "pulses" the negative side.
This wouldn't have worked to dim "channels" on a modified Finnex planted plus (turned the light into a 3 channel controllable fixture, long story,Finnex was neg ground)
Point is that using larger than what is inside MOSFETS you can control anything.
THE catch.. you need to invert the MOSFET . Internal is an NPN (positive gate).. the external signal (no wiring) of the TC-420 gives you a negative signal for the gate..
so you need PNP Mosfets ) pretty sure one could also do this w/ power transistors but MOSFETS were the easiest,
PNP Mosfets are "inferior" to NPN and finding large ones is a bit costly (well more so than NPN at least) and something to do w/ less efficiency so heat sinking may be required..
Need a bigger geek than me for that..
Point is you can "free wire" a MOSFET and resistor.. Your "gate" voltage can be anywhere from 9-24V..5 and under voltage doesn't work.
Note -10V gate..
Best fit is using DC to determine "safe drain" at your voltage..
@ 10V over 10A...
7-8A @ 12v..roughly.. 84w