Doing a ride this weekend and there is a 90 mile (145km) stretch without a fill station

The bike is a Mach 1 with a SS1 29D carb, Silentium exhaust, stock cam, road piston, and no significant other mods. Carb is reasonably tuned for air/fuel ratio. Relatively new wheel bearings

The manual says it has a 4+ gallon tank and gets 60 miles/gallon so I should be set?
Could be hilly roads, but I'm thinking anything over 25mpg should get me through... there is no way I'm under that right?
Ya I know, I know... the elephant in the room is the likelihood of going 90 miles without some mechanical failure
