Ah, that's right. Haven't done anything more complicated than arithmetic and minor probability calculation in a while. That makes this a lot harder. We also know that we can't go straight through because of the lake in the middle.
Alright, so that's ~2 days, ~3 days (slightly more than three), and ~5 days. We should probably expect... three to six days of travel to get there and a bit less to get back? That's rather an arbitrary ballpark, but other people with more hiking experience are free to make better estimates.
At the upper bounds that leaves us only two days to catch Kangaskhan (assuming that we take the downtime between travel hours to catch ours and Silver's instead of going out of our way for them), but I'm not inclined to be
that pessimistic. I'd still say we shouldn't expect to have more than a week of spare time to catch Kangaskhan-- in fact, we should probably expect much less, especially if Silver slows us down (he's the weakest of the party at STR 7). Always plan for the worst.
Speaking of which, this really doesn't give us much time to account for things going wrong. If someone gets injured, that will slow us down
catastrophically.
Hm, that might turn out to be less distance covered overall, if the extra stamina cost means we can't do it for the full six hours. If we can, though, it might be worth it to hustle through the Safari Zone South (where it's safer), particularly on the way back. Or maybe we could just travel for longer at a time instead?