Your chassis A/C cycling above 2800 RPM is likely caused by high head pressure from insufficient airflow at highway speeds, low refrigerant despite proper charge, or the PCM cutting A/C during high load conditions - this is normal protective behavior on Ford V10 engines.
Removing grill improves F53 battery access significantly. Use floor jack with wood block to lift 45lb battery to tray height, or get a helper. Battery carrier strap helps. Consider battery slide tray for future ease.
Since your ECU board is unrepairable and Ford/RV dealers won't help, try specialized ECU rebuilders like Module Experts or Solo Automotive Electronics, or search for used units on car-part.com with your exact part number 7C3A-12A650-DSC.
Flaking faux leather is common on RV seats and typically not covered by warranty on older units. Options are seat covers (most affordable), professional reupholstery (500-1500 per seat), or replacement seats. UV and heat cause material breakdown.
Georgetown GT3 Class A on Ford F53 chassis. Standard Ford maintenance with Dometic appliances and Onan generator typical.
F53 marker light intermittent failures usually stem from bad grounds or corroded connections. Check frame grounds, bulb socket grounds, and wiggle test connectors. Multifunction switch can also fail internally.
Beyond batteries: verify converter is lithium-compatible, add DC-DC charger for alternator charging. Choose LiFePO4 batteries with built-in BMS. Check if 2023 GT7 has lithium-ready charging system - some newer models do.
Yes, you can likely replace your 2018 Georgetown's original lead acid house batteries with lithium, but you'll need to check your converter's charging profile and possibly upgrade it. Most 2018 Georgetown models came with converters that may not have lithium-compatible charging algorithms.