Potentially doing this with a friend, I have a gravel/monstercross bike with 50mm slicks and a rigid (almost) 29plus single speed
From looking at photos, I see no massive hills but lots of grassy muddy single/doubletrack, and lots of proper mtbs but few gravel bikes. So I'm thinking my mtb may work nicely. Anyone done it single speed, or can comment on elevation?
Alternatively I'll get some knobblier tyres for my monstercross, although I could do without more purchases at the moment
I did it in winter when it was very wet. There were no awful climbs but there was quite a lot of soft, muddy and rutted stuff that despite the lack of elevation would be hellish on a singlespeed. I think in the dry it could be pretty good on a singlespeed but in the wet could be a lot of toil involved.
If you're happy on a singlespeed already its probably fine. As tomd says, no awful climbs.
If you need / want the paper map I have a spare.