Super C popularity has grown due to commercial truck drivetrains (Freightliner, Ford), diesel reliability, and better towing capacity. Class A offers more interior space per dollar. Choose Super C for drivetrain and driving experience, Class A for living space and value.
DEF low pressure with leak needs prompt attention. Check filter housing, lines, and connections for the leak source. System will derate engine if not repaired. Filter replacement is common fix.
For the Jamboree fridge, check LP gas flow, burner for debris, and 12V power. Ford 460 EFI conversion costs more than the RV is worth - maintain the carburetor instead.
Class A offers more space and amenities at 28-33ft. Class C easier to drive with better MPG. For your needs (king bed, large shower, recliners, tow SUV), Class A likely better fit. Test drive both before deciding.
Class B offers better MPG and easier driving but limited living space. Class C provides more comfort for extended trips. For 40-50 mile cycling days, Class C comfort may be appreciated. Consider small 24-27ft Class C for balance.
P0171 lean code with no drivability issues is safe to continue driving for your Florida trip. Monitor for symptoms. MAF cleaning was good step - may need replacement if code returns. Check PCV and vacuum lines when convenient.
E-350 and E-450 use same V10 engine with nearly identical 8-10 MPG fuel economy. E-450 has heavier suspension, brakes, and higher GVWR. Choose based on weight capacity needs, not fuel economy.
The 2007 3-valve V10 does not need EGR delete like earlier versions. Focus on regular maintenance: Motorcraft spark plugs, synthetic oil, and transmission fluid changes. Engine is reliable as-is.
Getting 11 MPG on a Monaco Knight 40 while towing a Jeep is excellent. Typical range is 7-10 MPG towing. Steady speed around 60 mph maximizes economy.
Your story is a perfect cautionary tale about how ignoring gradual performance decline can lead to catastrophic engine failure. The combination of blocked exhaust flow and oil starvation from running 500 miles with severe backpressure absolutely justified your decision to replace rather than rebuild the engine.
Tow/Haul mode works with cruise control. Use Tow/Haul for all RV driving - better shift points and engine braking.