150 watts of solar using Lance factory wiring????

With that short a distance the #12 will be fine. It's certainly not worth pulling new wire for the very small power loss.
150 watts should be pretty good for a small TC like you have. I have 100 watts on mine and it seems to do the job quite nicely.
I would, however, wire the panels in series and use an MPPT charge controller. I know they're more expensive but I feel the additional charging output and wiring flexibility are worth it. I recommend you look at Blue Sky charge controllers.