Get a tool. I don’t care for the cheap Park version. But you can get a decent Shimano or 3rd party.

Chainring bolts will probably cost as much as the correct tool and if you mess up the crank, the cost could be as high as getting a VAR chainring bolt tool.

The slotted nuts can be a pain, but I have never cheapened out and tried a dime or some makeshift tool that was not well thought out; especially with a triple.

John