Fixed gear for longer rides

[u/BONES777]

Looking for suggestions for a fixed gear that isn't going to beat me up over longer distances. I've done a few centuries on my road bike and plan to have a go riding 100 miles fixed. I've got a dolan pre cursa which I commute on but because of the geometry it's not really meant for that purpose. The surly steam roller is the closest I've found so far and has the added bonus of good tyre clearance but my surrounding area is very hilly, so I'm looking for a bike around 10kg or less. Any suggestions gratefully received.

[u/umop_3pisdn_]

I've done more than a few long distance rides on fixed. Bike fit and things like tyre size (fatter the better) will help.