IMO you are wasting money and effort going MPPT with the three 50s.
As previously stated in your other thread on this, IMO you should just get the Bogart solar controller that goes with your Trimetric 2030 and put those three 50s in parallel. Amps to the battery will be nearly the same. ( I have three 100s and have tried both ways and it makes no diff)
You might find your 150w is enough for what you do. Right now you are just speculating you will want /need that fourth 50. If you did turn out to want/need it, you can do better by ditching one of your free 50s and getting say, one 160w panel if it will fit, to make a 260. With PWM, you can mix panel sizes easily, no worries about matching so closely so to not confuse the tracker in an MPPT.
So your best move is -- install the three 50s with the Bogart PWM and try it out camping. Then you will know what if anything would be a good upgrade. Since 150 is a lot for a truck camper usage of 12v, it is quite possible that you won`t need any upgrade.
