Here's my take.
There is curently no holder of the UCMA HAMR (Highest Annual Mileage Record), because they've only just set the rules. So which ever rider is first to submit a valid claim will be the first to claim the UCMA HAMR record. Assuming his team's admin is up to scratch, that's likely to be Steve A, because he's got a ten-day head start.
There is currently a sentimental holder in the world's eyes of the record for highest annual mileage, and that's Tommy Godwin. The first person to get to 75,000-odd miles within the course of 365 days will be entitled to claim that (in the eyes of the world) he (or she) beat Tommy Godwin's record and is the new holder of the record for the "one-year time trial".
All of that is backed up by the UCMA rules:
Note: The record by Godwin was never officially certified by any sanctioning body, though Guinness Book of World Records did offer belated recognition of Godwin’s remarkable achievement.
So any rider making an attempt per the rules below can get a record certified at a mileage below that recorded by Godwin, but we all know that Godwin’s mark is the target. The corresponding target for women is the mileage of 29,603.7 miles logged by Billie Dovey in 1938.
The UCMA have ruled out a claimant for
their record doing something sneaky, like paying $300 to enter, riding for one day and then submitting a claim, by stating that a year lasts for 365 days. That implies that you can't submit a claim until 365 days from your start date.
For what it's worth, my money is still on Steve A for "both" records. To put things into context, with all the benefit of balmy weather and tailwinds, Tarzan is only one day ahead of Steve after he's done 18. Tarzan's plan, such as it is, involves complex and risky travel manouevres around the monstrously large country that is the USA. He's so far only managed one long day. We know from his experience that Steve is capable of multiple astonishingly long days.