I always bring my tow belt.
Much of your other group gear works for a single person. First aid kit, radio, group shelter, spare cloths. If you bring it, you are much less likely to need it.
As for the tow belt it's something that I won't go on the water without.
If I need to scramble up on rocks I can attach my boat to me and pull it up.
When I am solo I am more diligent about pulling my boat out of the water and tieing it off am I am going to go on a walk.
It allows to to float your boat if your at a place where you can't take it out (someone else's dock etc).
Help others in need.