p'lax = paralax.
thatz the brand of AC 115v charger/converter in the stream.
oem for your model is a 73xx series i think.
u can read about 'em here or out in space.
the tristar accepts solar/wind/hydro but NOT 115 v ac.
charging from a DC source is different than from an ac source.
perhaps there is a charger unit that does AC and DC but i'm not familiar with it.
ac power must be CONVERTED to dc before jamming it in the batteries.
dc fuel (from what ever source) doesn't need the conversion step.
it's NOT absolutely necessary to replace the p'lax
but the oem unit is UNDER sized for 4 batteries and doesn't have true BULK and float stages.
yeah i knew the 27 inch mac sucked lotz a juice but let u declare size and power needs.
a laptop is SO much easier to use boondocking...
((spare battery sources, lower consumption, NO big inverter needed and so on))
it is technically possible to combine 12v and 6 v batteries
but further complicating this stuff with those details only makes it all more complicated.
while a genset IS backup for solar, it might be wise to START with a genset...
they are easy to find used and easy to sell.
solar once installed is very hard to pass on...
it's still not clear what u will use for towing,
but it would be simple to have 2-4 additional batteries IN the truck bed
and hook them to the solar charger OR shore charger when parked...
all the batteries are 'lead acid' the difference is flooded/wet cells vs a water/acid absorbed matrix in the agms.
and WHAT about a sam's club tag
suggests they actually came from sams...
those batteries could be GOOD for 4-5 years if not OVERLY discharged and properly maintained.
i'm ALL 4 solar and have it topside,
but one can buy a genset capacity for way less money.
on a HUGE moho having 6 or 8 or 10 batteries is not an issue, but the big boys all have gensets to REFILL 'em quickly.
much depends on WHERE u will be b'docking and what season.
i like parking in the shade whenever possible and going NORTH is the hotter times.
if u r planning to hang in tx/az/nm/socal the sun is easier to utilize.
it's all good.