Don't many controllers require that you have a battery connected before the panels are connected lest the controller die an untimely death? If you have one like that, connecting to the load side would toast the controller whenever the disconnect switch is disconnected.
Few RVs disconnect absolutely everything with the disconnect switch. Trailers have (or should have) the breakaway braking system wired directly. Often other safety systems are also not disconnected, things like LP and CO detectors. Things that need large current levels, like big inverters and generator starters, are usually wired directly. Sometimes the converter, if a deckmount unit not built into the electric distribution panel, is also wired direct. A solar installation is in good company.
