I finally got a kayak on the roof with the Mako Aero kit. I have some pictures to attach below.
First, the kit is marketed as for either the sit-on-top kayaks, which have a flatter hull, or the sit-in kayaks. They seem to be optimized for the sit-in kayak, but somewhat adapted themselves to the sit-on-top kayak that I have.
Second, there is no hook under the front lip of the Highlander to the attach the hook to, but I found a steel cross-member with a drain hole in the bottom. I was able to attach the hook to the cross-member this way. Held securely and I didn't have to worry about damaging the plastic underbody cowling.
Third, as someone one here or somewhere suggested, I bought some foam pipe insulator and wrapped it around the straps to avoid damaging the paint and grill of the Highlander.
Yes, it has been rainy and the vehicle needs washing quite badly.
I drove the kayak from my house to Inks Lake State Park (West of Austin) and back, about 60 miles round trip without issue. The Mako Aero kit attached well to the factory aero roof rails and held the kayak securely at highway speed, though is made a lot of wind noise. The Highlander is a tall vehicle and I am 6'4" and was able to load the kayak on the roof without banging the vehicle, but most people would probably have a bit of difficulty with this. Maybe a small step ladder or second person would be good.
Anyway, I kayaked and had fun and didn't have issue with the rack. This is probably a good solution for kayakers who have a Highlander.
I have a bit more info and pictures on my blog about the thing.