I agree, not a job for a mower, but more for a rotary cutter to knock it down first then maybe and that is just MAYBE run back over it with a mower. Even then the surplus growth will tax the belts on a mower, although some of the better ones will go thru it with no problems. I would probably attempt it with my Steiner 525 as it has plenty of power, good belt setup, and hydrostatic so I could creep into some of the thicker bunches without overloading the mowing deck. Still could be a problem with hidden items, that a rotary cutter would take in stride (and throw across the yard). Layering the cuts, first high and then lower when you can see might be a smart move, but requires double cutting.
If you have already done this, and didn't tear up anything, good job!!!
David from jax