For half the price of the power tool with its motor, blade, housing, guards, assembly costs etc you can buy this single piece of plastic which will, despite the obvious cost issue, revolutionize your circular sawing world.
https://www.toolstation.com/stanley-bi-colour-quick-square/p15505 for cutting planks and notching posts etc just put the blade to the mark, press the lip of the square against the plank next to the saw and get a pretty much square cut every time with no messing about clamping the guide X mm from the cut. For your next job. Like Blup says you'll be using it like a handsaw
I was going to say why don't you burn the wood in place. Its so uncommon to smell a bonfire these days seems like no one does it so i looked it up and it is still legal as long as not causing a nuisance. But then the wood is probably full of chemical treatment, you scorch the earth, still have a pile of ash to deal with... Its an option though