Solar panels.
If you will not be living in the RV in the winter, then solar panels will keep the battery full, without the noise of the generator, or maintenance.
A pair of 140 watt panels should do the trick. $229 each. Consider they will still be making power 30 years from now, that is less than $20 a year for power. And you should be able to sell these panels in 10 years for close to what you paid for them!
SunElec.comLook for 12 volt panels and a PWM controller - 20 amp ones should be in the $35 price range.
AS for the black tank, I would not remove it. It might be useful someday.
For the grey tank disposal, what I did was buy 30' of drain line. It has 3/8" holes spaced every couple of inches, and 4" outside diameter. Cost was nominal - like $8 per 10' section. I installed a clean out tee, so it has 10' one direction and 20' the other direction. It was buried about 15" underground, and handles all my grey water needs while living in the RV full time. Black water could have been drained into the same line, if it had been buried about 4' deep. But I did not want the smell to come back to the surface, and worried about it clogging with debris should I drain the black water into it. If you used about 60' of the drain line, and buried it around 3' deep (using a trencher or other thing like a backhoe) then you could fairly safely put the small amount of black water down that hole, and it will dissipate. Not 20 gallons a week, but the amount that a RV puts out on a weekly basis.
Have fun full timing!
Fred.