The 90 degree elbow is an excellent idea - really reduces stress on the connector and cable.
Installation of a hard-wired unit would not affect your RV warranty and would be a much better option than portable/exterior. The EMSs are MUCH more than just "surge protection." Their most important functions are protecting you from the more common under- (most frequent) and over-voltage situations as well as ground issues, etc. Our PI 50 amp hard-wired unit has a remote display that tells me the voltage and amp draw on each leg. It has saved us thousands of dollars in appliance replacement/repairs in the almost 2.5 years we've been full-time. Unless your converter/charger fails or you leave the rig unplugged for long periods, a separate 12V monitor for the house battery is unnecessary.
Rob