What generator model is it?  Very common is the Onan KY ("KY" is in the model number; the name on the outside has changed once or twice, but MicroQuiet 4000 is one of them).  On this generator, the side of the green outer case of the generator proper comes off with a couple of cams to give access to many bits of the generator.  Unfortunately, this does not include the starter, which requires removal of the outer shell to get at (and hence removing the generator from the RV in most cases).
At least in my motorhome, the generator is mounted to a sub-frame with a couple bolts at each corner.  Dropping it is conceptually pretty straightforward:  disconnect the wires and fuel line, hold it up with a floor jack or whatever, remove the bolts, and lower the jack.  I'd suggest checking the clearance underneath with a tape measure first as it may be necessary to park the RV on ramps or otherwise block it up to have enough clearance under the skirting to pull the generator out.
Before going through all that work, I'd suggest verifying that the 12V power and ground connections are all good and tight and that there is sufficient voltage when it's cranking.  A poor connection (causing inadequate voltage) will prevent cranking.
The box by the differential sounds to me like it may be a spare tire carrier.  If it is, there should be some sort of a crank connection (often with a bolt head like end under some sort of a cover) that will raise and lower the cable.
I haven't heard of anybody attaching power locks to the entry door.  I'm not sure how well it would work with the typical RV door latches; certainly they aren't designed with that feature in mind.
I hope you do realize that an analog TV antenna is the same as a digital TV antenna.  The frequency ranges used for TV broadcasts have not changed.  You just need a digital tuner to receive the digital broadcasts.  (At the RF level, all the signals are analog, after all.)