Other than (I'm guessing) your zip code, I know nothing about you, what kind of camping you plan to do, how many will be camping in your new RV, etc, etc. What I think are necessary items may or may not be important to you.
If you are planning to do much camping off grid you will want at least 2 batteries, 4 is better. A good converter and maybe an inverter, but there is no point in getting a big inverter unless you have a big battery bank. A generator is a good idea too. If you are always going to use campgrounds for camping, not much point in any of the above.
A lot of the things that you would pay extra for you can install yourself if you have reasonable DIY skills and the time to do it. You can save yourself a lot of $$$.
I tow a car since I am a sightseer. Park the RV and sight see using the car. If you think you might want to tow a car, have the dealer install a 5000# hitch. That's also useful if you plan to carry bicycles with you.
Enjoy your new RV.
