The red paint on the 250 tank is so jewel-like that I just can't bring myself to mar it up with a tank bag, pads or protectors don't keep the finish pristine.. Looking at the bike for the first time today in bright light, Honda really pulled out the stops on the finish of this bike. It's really first class..
About a top box, one good thing about the Givi TopBox solution is that it sits were the passenger would sit so the weight is more centralized (but not as good as being on the tank). Hopefully, being right behind the rider will help with the air stream as the fairing and rider will channel a lot of airflow around the box..
I've admired the F650 design.. I've seen people locking their helmets in that 'tank' depression using the rails that you mentioned as lock points.. very nicely done.
Yeah..... I admit that keeping a bike looking pristine has never mattered for me. I just like to keep 'em running and use 'em. My formative years on farm bikes are probably responsible for that. I'd had my MB100 for more than 10 years without doing anything other than necessary maintenance. My nieces wanted to make some money, so they offered to wash it.... for the first time.
After working away for a long while it was "Uncle Michael, we can't get all the dirt off your motorcycle."
I praised their effort and gave them the agreed fee.
That was about 15 years ago. The MB100 has not been washed since. I haven't used it for ten years, but some young fellows have been using it off road.
Re using a backpack: I discovered long ago that it is better to have the vehicle carry the load, not myself, even if it is only a small backpack. I know it looks dicky, but it works; I have a basket on the front of my bicycle (which doesn't have suspension), as well as a carrier on the back.
In hi-tech Japan there are millions of "sensible" bikes just like that. I worked there for a couple of years.
I cycle for everyday commuting, and a bit more. I use my motorcycle for high days and holidays. When riding, it always carries my backpack, not me.
The Givi topbox sitting in the pillion position sounds like a good idea.
There was a system called Pak Rak available some years ago (in NZ, I don't know about elsewhere). It was elegantly simple, using a fabric bag with a mounting pocket in it, and a carrier with a removable frame for the bag. With a pillion it could be mounted on the carrier. Without a pillion it could be mounted the other way around, on the seat.