Treasured Live Oak Maintenance - Who Do You Call?

That is a whole lot of beautiful shade. How many swings does a man need!

If there’s nothing wrong with them, leave them alone and they’ll do fine. Fertilizing them at that age will have minimal, if any, effect. But if you really want expert advice, I think you answered it in your last sentence.
I called a parish extension agent about 30 years ago about some live oak freeze damage and someone came and looked at it (Ouachita parish). He said don’t do anything and he was right.

I have family who have some decent acreage where three generations now live. Across that acreage that isn't wooded or pasture they have probably 40ish good sized oaks. One thing they have done that I wish others would consider doing with younger oaks is keeping them pruned just high enough to be a good shade tree, where they can be easily mowed and walked under/around. I think with oaks having the access to see those lower limbs adds so much more. You can walk through and around their's and get a close look at what is calling those oaks home. That could be pretty cool for kids, too.

This year I've started posting observations from their trees on iNaturalist, and that list has grown considerably in these past few months.

Had a tree pro out to check our oaks, remove dead limbs. I asked him about removing the limbs touching the ground to lift the canopy. He said if they were his trees he’d let them be. It’s natural and provides a better habitat for critters. YMMV

Marathon Tree Service was the go to guy for live oaks around Baton Rouge and he had the contract to take care of the live oaks around LSU. He was getting close to retirement a few years ago but if he's still around, use him.