Thanks for the responses.
I'm doing it solo.
I've done two solo before:
1st time I changed to another pair of shorts after 12hrs, had some cream on all the way through. My arse was okay until about 6 hrs to go.
2nd time I changed shorts every 4 to 5 hrs and didn't bother with any cream. Arse wasn't too bad until the very end.
I've never had blisters or blood involved so maybe I should count myself lucky.
The pain in my legs will take my mind off the pain in my arse anyway.