I helped on one install, Thor gasser, that went down through the top of the right rear cap and down to a low point of the rear bay, which in his case is an outdoor kitchen, forward to the next bay where batteries are and bolted the 60 amp charge controller to upper part of the bay. Then short run to batteries below it. So far, so good and his went on six or so months age with no problem yet. He's camped next to me at the beach this week and his 8 100 watt panels and six GC2 batteries seem to be supporting his coach and Whirlpool res frig pretty well; overcast mornings and all.
BTW, 4 ga seems a bit hefty. Run your panels at least pairs in series to a junction and it would take a big bunch of solar to need 4 ga down from the junction box. I have three pairs of 100 watt panels, to a 6 ga welding wire ( Windy Nation through Amazon ) and only justify that big wire "in case" I decide to add 2 or 4 more panels later.