We are all getting older. My wife tells me I'm included.
You may be making this more complicated than it needs to be. If it was me, I'd buy the red top to start the engine and the blue top for the coach.
I do not buy Optima batteries. For the coach I purchase Discover AGM batteries. Newmar is now putting these in coaches as standard equipment. To start the engine I buy the highest brand name cranking batteries (I need 2) I can find.
Your coach may have the solar (5 watt) charger that trickle charges the engine battery.