Forget exactly where the race is, but I think I remember it as being south of here. It was 65 at Greenbelt this afternoon! And I didn't mind running in the snow, choosing to run in the fresh snow next to the trail many times.
It's in Spotsylvania, Va. There are two days in the 60's due there this week, plus a good bit of rain. Here's their weather forcast - wow - 68F and thunderstorming on Wednesday. Should melt snow and provide lots of mud. https://weather.com/weather/tenday/l/LAKEANNAVA:13...
Do you have a goal for the race?
Contingent on MUD, I'd be not unhappy with anything over 50km. One loop configuration would be 31.5mi., another 32.9 and so forth - of course I'll be brain dead after five hours and unable to "configure" clearly. Nice run yesterday, BTW - I assume you waited until things were slushy versus frozen footprints.
No real choice for conditions so I went when I felt good and rested. Good luck with the race. With your training I am sure that you won't good brain dead after 5 hours. Especially not with Hugh helping you along.