got several thoughts on this...
1st - does anyone else think that katy, jungle cruise tour guide, looks like one of the spice girls? LOL...
2nd - felt sorry that they didn't make it. they were close. seemed like a lot of crossing the parks and extra park hopping. understand that fastpasses, lines, etc. had a role in that..
3rd- I actually believe that it is doable. here are my thoughts on it though.... could be all wrong, but it wouldn't be the first time. LOL... anyway, here is what I would do.
I would go during a slower period where the parks aren't as packed. shorter lines, that sort of thing. like middle to late September.
I would also do the fastpass+ to get the passes for the rides that are more popular and have longer lines. I would, however, put the passes of the rides in the same park closer together so that the only park hopping that would be done is when each park is complete.
get ride times for all the rides. I know this does not include lines, but at least this way I could get a better idea of how long each ride takes to ride to factor in.
get a map of the parks and see where each ride is located and do my best to calculate time it takes to walk to each ride, guess as best as I could on wait times ( could use a wait time app to get a better idea on that), utilize single ride lines if possible and try not to cross the parks as much as possible to cut down on time in between rides. i'd do what I could to go from ride to ride that are closer together as best as I could instead of crossing the parks. I know this will happen somewhat, but I would do my best to cut that down as much as possible.
i'd probably start off in epcot, then head on over to animal kingdom and knock it out quick, then head on over to hs and knock that out, then finish in mk taking advantage of smaller lines during the electric parade and fireworks display.