There are many different types of guards, and I am by no means an expert. I have a pair of Lizardskin shin guards that work fine, but they are all going to to be hot. The Lizardskins were also made for people with longer lower legs than I have so I had to cut them. I am currently searching for something more comfortable. Some of the more experienced wommen here may have suggestions on better guards.
I would not recommend Town Run, I won't go there myself right now. The problem is the trail is highly popular with people who ride it for speed and time - and apparently a good number of them aren't looking out for slower riders. I've been warned not to ride that trail by everyone I know during the evening or weekends, I am still pretty slow so am listening to my more experienced friends. I will eventually try it during the middle of a weekday.
I was referring to the new beginners loop at Fort Benjamin Harrison State Park in Lawrence. You can find out more information
here and a map to the park and of the trails
here. The beginners loop is the one in green on the west side of the park. It probably isn't any longer than the trail you have in Avon so it may not be worth your drive, but I wanted to mention it.