I am not sure about the sunseeker. if I ordered a diesel genny for my Prism I would not have received an AGS. It did come with an auto transfer switch (my LP genny does not have that feature).
I priced out an AGS from Cummins- approx $400 for the wired and close to $900 for the wireless. The AGS will monitor the chassis battery, the coach batteries, and the temp. It will start and run the AC , charge batts etc It will even auto top off batteries ahead of the cg quiet times It is fairly easy to install. Especially to the batteries. The thermostat is more difficult. I have a dometic digital stat and the AGS needs a 12V signal from the stat to start the genny. I can not figure out that hook up.
PM me and I can send the full manual/install guide