I have found a local route that's used a lot by roadie groups and safe and flat enough long enough I'm giving a 50 a try this spring. It's out by Butner where grandpa Madhoff is in prison. It's also normally neutral cross wind, meaning a plus for a disc rear wheel.
I'll give it a go. If my 25 pace was over 25mph, it's going to be really really close for a sub 2-hr. In training now I'm within 7w of that 25mi pace from 2020 for 90min rides on the TT bike of challenging hills/corners. Stands to reason if I can meter the effort better on flatter terrain I'd gain a watt or two.
Realistic goal is 125min. Good training opportunity. Needs to warmup though in the mornings as I would be doing it at sunup for no traffic.