For me it's a question of whether or not those 160 watts of solar are ever going to get those two 6's to even near-full; for days at a time even. If not, the setting doesn't matter... the OP will be charging via gen power. And at 8 amps, the 14.4 solar setting would do just fine, up to ~ 80%.
But for sure, if the chance arises to do a solid near full charge (at the 14.8v setting), followed immediately by a top, or finish charge at the controller's 15.3v setting, then do it, and call it a good days work. Not every day of course.
I guess what I'm saying is, set it to the 14.8v setting, (temperature compensated), and be sure to do a good 'full' charge every hundred miles or so, depending on weather and gennie use. And yes, do as Mex suggests, and, jot down some readings along the way. You'll understand them better later.
