500 Euro Yammy XJ600 has a place it seems https://youtu.be/tEqh79SCZSM
XT600/660, upgraded suspension, bigger tank, soft luggage, decent rack for a roll bag
On the contrary , sounds like a top trip to me…
Economical enough to allow a small tank but still have good range.
Well I started on a Royal Enfield 500 Bullet, got as far as Thailand before realising it wasn't going to make it around the world. Then went for the GSA 1150, got it shipped out from the UK, beast of a bike, great for munching miles and corrugations but then opted to swop it in Australia for a XT660R for the benefits of riding off road. No regrets on any, as when you're on the road nothing stands in your way of finishing off a days riding with a smile on your face.
No matter what you ride or where you ride, you'll have a great time. Don't worry about what shit you need or don't need, get out and hit the road as soon as you can or suits you, as you never know when your time is up.
Don't worry about riding with a group or on your tod, as with the latter you'll have a better experience with getting to know the locals.
The money you save on buying a flash new shiny motorcycle would be better spent staying out on the road, if it's an old nail you buy then you'll get to know the locals even better. your carnet would be cheaper, the bike would be less prone of getting stolen and if it did it's less money you've lost and if you do choose to insure it, that would be cheaper too.

* I know the question references new bikes... even hypothetically I can't bring myself to buy new! I'd be off RTW for about £6k...