Regardless of how this run goes, he does appear to be actually doing it! Looking through his Strava data, nothing immediately strikes me as being odd.
Will C pointed out that William Goodge's heart rate was too low for what he was doing. His supporters claimed that this was due to watch errors. I also argued that he might simply be a better athlete than his previous race results suggested. (I'm less convinced now, as he hasn't shown any decent results since either.)
Will also pointed out that Paul Johnstone's cadence suffered mysterious drop outs lasting several miles, which were explained away by his supporters as watch faults or using poles. However, using poles only drops your cadence slightly- try it for yourself.
I also like the fact that he's carrying the tracker. Not only is it an independent verification (GPS rather than phone signal) but it also gives his position in real time and enables outside observers to keep an eye on him. Neither Goodge nor Johnstone did this but funnily enough Pete K and Marshal Ulrich did.
The two easiest ways of cheating in these events are:
1) You hop in the van for a mile or two several times a day which would be very hard to spot especially out West. It would make each day a bit easier, but the van would have to drive carefully to maintain a slow speed. Your cadence and heart rate would drop (unless you are doing pressups and waving your arms like a loon)
2) If you are more organised, a better plan would be to have a substitute who takes your watch the moment you hop into the van and runs for you. The van can then travel at a normal speed (with you resting inside) and wait down the road for the substitute to catch up. The other runner's slightly different cadence and heart rate might be detectable though, depending on how well practised the team was.
This run doesn't seem to have anything dodgy about it. Please correct me if you think I'm wrong.