Don’t know your specific situation but I see three options.
1. Be patient they will eventually rot.
2. Hire a dozer, they can remove them quickly and smooth things up when done.
3. Hire Forestry Commission to plow firebreaks and remove the stumps.
i have done all three and they all work eventually, some quicker than others.
Bite the bullet and hire an excavator and/or dozer and get it done. You won't regret it. When I last thinned pines, I expanded our largest field from 4 acres to 6 acres by clearcutting a section of the pines. Brought in an excavator and dozer to clean it up. Excavator popped the stumps and dozer cleaned it all up. Done and over with and no stumps to worry about going forward.
Rent a mini ex or backhoe, you can get a lot done in a day with a little skill. Not sure where you’re at but there’s a great rental place in Warner Robins with all kinds of equipment. Powerhouse rentals, I’ve rented from them instead of hauling equipment from Florida.
If you can work around them and leave them to rot it will actually help your soil and plot in the long run. Cut them off as close to ground level as possible, round the edges of the stump a bit so stuff doesnt get hung on em, and last take your saw and plunge cut an x pattern in the top of the stump. It will hold water making it rot faster. It will also hold water for the plants growing next to it. That is the hippie way to deal with em.😉
I will never forget the day (I was about 7 or 8) when Dad and a powder monkey from the rock quarry dynamited the stumps out of a field at the Farm. They were old stumps mostly 36+ inches at the ground. We would get under the wagon when they shot one. That was better than any 4th of July I have seen since and I have seen a lot of them.