Might have been more feasible if you could cross the road directory from 28 - 20.
Worth a shot though
I think there was basically one route it could be done by someone quick enough but I'm not sure I could recall it even with a map in front of me - the tricky bit (as well as the road crossing pinch-points) was there were a number of places with 3 parallel controls or sets thereof - so one is the outward leg, one is the inward leg, but when do you get the 3rd one?
OK, I think this would be the way, with the inside/retrospective knowledge of where the climbs would be. Can go either way, but I'd start with the riverside run rather than the climb out of the event centre, and the 400m side trip to number 2 could tack on the beginning or the end. 7.6km straight line, so would take a lot of hard work! The trickiest bit is where to fit in 12 and 13, I can see 2 other options but they would create more ups and downs.