I can confirm your observation that Winnebago wires the Generator 12 Volt Power connection to the Coach Battery System, on my RV the positive wire runs directly to the Coach Battery Isolation Relay Stud.
There are two ways that Winnebago Coach Generators are wired, on coaches with 30 Amp Service: I can't say if you have a 50 Amp Service RV.
#1: The Generator AC output is cabled to a 30 Amp Receptacle, located in the compartment where your Shore Cable is stored. To power the RV with the Generator plug your shore cable into the receptacle.
#2: The shore cable and the Generator AC output are both run into a Transfer Switch Box. If there is no shore power, the large contactor in that box ties the generator output to the cable that runs to the RV breaker box. If there is shore power applied, after a short time delay (usually 20-30 seconds) the contactor operates and connects shore cable to the cable that runs to the RV breaker box.
BE VERY CAREFUL OR HAVE SOMEONE QUALIFIED DO THE FOLLOWING: 120 AC can kill you if it comes in contact with your body.
#1: You can start the generator and try to measure for 120 Volts AC across the Hot and Neutral on the receptacle, using a meter set to AC volts and a range above 120 Volts.
#2: You can remove the Transfer Switch cover and with shore power disconnected start the generator and measure for 120 Volts AC on the terminals where the black and white wires coming from the generator are connected. You can see if the transfer switch is good by measuring for 120 Volts AC on the black and wires coming from the RV electrical box.
Randy - Manhattan, Kansas
2015 Vista 27N
2016 Honda HR-V