There is three of us and the other two are not as strong as me! However it was there choice to do it in 2 to my surprisement!!
If they are seriously struggling then the van can pick them up and they can pick up where they left off, or they just might have to miss sections out but can't see them wanting to do that.
I think we have probably underestimated it so we shall see. It's going to be fun either way
2 Days off road will mean some long days in the saddle and not a lot of time for hooning around. Worse case if things are looking dicey on day 1 you can cut out some of the slower off road sections. the last third of the trip is a downhill/flat blast so don't be too worried if you think you are behind schedule. Having said that - don't bother with the Old Coach Road, you won't enjoy it without an MTB and it will be a big time sink.