They added a whole lot of miles and a couple of non-trivial hills just so you could follow some valleys. The southern end of Wexford Run has a tough little climb, followed by another a mile later on Brandt School.
You're not gaining anything by sticking to two-lane side roads. Frankly, I'd just barrel straight down Perry Highway. A good bit of the Wexford Flats area is halfway tolerable, now that construction of the worst part of it near the high school is done (NOTE: I haven't ridden it, but I've driven through it several times.)
In the construction area, especially where they have it to one lane each direction, TAKE THE LANE AND HORNS BE DAMNED. They're not going to be blowing through there any faster with machinery and cones all over the place, so I wouldn't be the least bit worried about holding them to 15 mph or whatever.
There are other ways to get south, too. Let me do a little digging on the board for a thread that came up a couple years ago on a similar request for info.
Background: I live near Perry/Perrymont near the Ross/McC border, and travel Perry almost daily between there and West View, where you have lots more options too detailed to go into here.