45A array won't generate 45A on 30A PWM, but having oversized array - with this particular controller - will be beneficial in low-light conditions. With PWM you normally have to under-size by 20%, but Trimetric monitor will clip the excess current, so you can over-size.
PWM with 12V bank "favors" low-wattage arrays. You have to use 12V panels and wire parallel only. With arrays larger than 300W this becomes awkward. Besides, there are fewer 12v panels on the market now, less choice, more $/W.
The OP with his planned 100-200W portable - he says there is always some sun within 20ft - will be fine with PWM. I would stay within 100W though. Too much weight and bulk.