We are picking up a new 257BHS this weekend and have been looking at the solar options as well.
We are coming from a Geo Pro with the 190 watt roof panel and 30 amp controller, so we have done some digging on the Freedom Express stuff. There should be a connector on the roof with cabling run down to behind a panel on the camp side of the passthrough storage (it's behind the little finished panel on the left). That's where the controller would be mounted (Freedom Express uses Jaboni controllers, but another brand may work). My understanding is that's where the "prep" or "ready" stuff stops. You then need to get wires to the battery location from the controller location.
The Jaboni's can have an external display or I think they Bluetooth to an app for the charge and battery state info.
Right now the wife just wants the "necessities" and solar isn't one. I would rather her be on board with it so that I can stay on board the camper at night