Sounds like you answered your own question, but when we purchased our TH we didn't think we needed one either. Toyhaulers and boondocking kind of go hand in hand and it is our preferred method of camping. We purchased a TH to enjoy riding and still have all the amenities of home when in the middle of nowhere, we have used our genny so much more than I would ever have imagined.
You don't need to get an onboard generator although it could hamper selling the rig down the road as the majority of toyhaulers have them, but an inverter 2000 watt generator might fit the bill if you don't plan on trying to power your AC unit. Run most everything including most microwaves and will provide battery charging should you decide to camp without hookups. Ultimately your $$$ your call.
Have many great times in your new TH!!!