Steve, sounds like you have an excellent grounding system that is extremely important not only for radio transmission but also to minimize lightening strike damage.
A secret I learned about 60 years ago from a Master electrician. How to install a meter center ground rod WITHOUT a hammer‼️
With a bucket of water, simply pour a small amount on the ground where the rod is to be installed and begin poking it into the ground. Continue to add water as you continue the process. Within 5 to 10 minutes that ground rod will be in the ground without a single tap of a hammer.
If you could share the signal strength readings you’re seeing, that would be extremely helpful.
I believe this is the radio you’re referring to:
Best wishes 