Suburban SDN2U thermocouple position issues are known on 2024-2025 models. Adjust thermocouple tip position to match working burner - should sit in outer flame cone. This is likely warranty repair on new Jayco. Document issue before DIY attempts.
This sounds like a main electrical supply issue, likely from your shore power connection or inverter system. The E7 codes and simultaneous failures point to insufficient power reaching your high-draw appliances.
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Your comprehensive rebuild plan is solid, but focus on structural integrity preservation, proper moisture barriers, and weight distribution. Critical areas include electrical safety, plumbing rerouting, and maintaining slide-out mechanisms.