I'm finding this an interesting topic.
Looking at the results for 2019, the winner took just over 5 hours and the average (median) times were around 10 hours. There was a 12 hour cut-off and about 30 of 230 didn't finish.
The elevation gain has been reported as being somewhere between 4,000 and 5,000+ft and the distance is a little less than 32 miles.
I reckon that under 10 hours should be doable, given favourable (or at least not unfavourable!) conditions.
Obviously, this being the Long Distance Walkers Association, running some or even all of the route isn't just acceptable but pretty much expected
. The elevation profile shows lots of steep ups followed by what I imagine are jog-able downs.
Entry would require a longish drive and an overnight stay in Swanage and (presumably) a couple of LDWA memberships. I'll have to see what my wife thinks... An alternative would be to do a virtual version of the same distance and elevation gain, but using Kent's coastal paths rather than Dorset's.