Bad idea?

If we ever dry out, I am planning on using my Stihl FS45 (with one of those solid heads) on the cattails in the ditch in front of my property. I already talked to the county, and they said go for it.

My LT will not get down there, too steep for the most part. I could see if a neighbor (farmers) would be willing to come over with a real tractor, but doing it myself sounds good.

Or, should I go rent some type of heavy mower/wacker?

Also, should I spray first, or cut 'em down then spray?

Thanks