This drought and heat are pretty brutal... It's amazing anything survives.
We planted a couple of red oaks (one shumard and one texas) at my parents' place down toward corpus christi last fall. The texas red oak was a small sapling, and the shumard was 5-6' tall. The shumard has been having a rough time (some brown on the ends of leaves) but it's hanging in there. The little texas red oak started out great, pretty much doubled its size and was full of beautiful green foliage. Then almost overnight its leaves started turning brown. At this point we started some emergency foliar spraying of a mixture of garrett juice, super thrive, medina plus, etc... There were a handful of leaves left at that point with some green on them. But before long the tree budded out, and now is full of green leaves again! This was just a few weeks ago.
First of all, do some research on this site about the sick tree treatment (sounds like you already have with aerating the soil and getting the excess soil off the trunks). Make sure you've got some compost under the trees and put a nice blanket of hardwood mulch over that. Don't water too often (we were doing it once every 2 weeks, then as it got hot, once every week, now more like once every 3 or 4 days... the heat is intense down there) but when you do, water deeply. But you also don't want to drown the roots so make sure you have good drainage... Some have said you're more likely to kill a tree with overwatering than underwatering. We're using a system of 5-gallon buckets with a small hole and tube for watering. This way you can meter how much water you put out, and you can add garrett juice, fish, compost tea, etc to it.
Remember that the tree can take in nutrients and water through the bark and leaves so I think daily (at least) foliar+limb+trunk sprayings (make sure to do it late in evening or early in morning) are a good emergency measure for a tree that's in really bad trouble.
The thing to remember about trees is that the real core of the tree's life is underground. It can lose the entire top (if its at least somewhat established) and still use the energy stored in its roots to resprout. So I definitely wouldn't give up hope. The trees are probably still alive (hopefully the roots weren't killed with overwatering), but they need some serious help. Hopefully they can bud out again, or worst case come up again from the ground. Good luck!