Trees can help filter air pollutants through their leaves.
Planting trees like spruce, pine, cedar, and yew might act as a barrier to the smoke once the trees are tall enough.
As for the propane tank, the propane company needs to get a large truck up to the tank and then the serviceman needs to easily get the hose to the fittings. The other spaces are available for planting as long as the plants will not reach the tank. Especially if you do not own the tank.
The other utilities also need to have access for repair and to read the meter. To be safe a call to the utility companies would answer as to their requirements.
There is a phone number to call to have the lines marked so you don't dig into the utility lines.
Here are a couple of threads that you or others might find interesting about dealing with smoke:
https://permies.com/t/163811/wildfire/houseplants-clean-wildfire-smoke
https://permies.com/t/91527/personal-care/purity/Ways-cope-thick-wildfire-smoke