Pulling a rough cut mower ok? (Sustained pulling capacity)

Hi,
I am still kind of new to tractoring and have a question about working a machine (and how much). I have a John Deere 445 with about a 1000 hours. (Gas Kawasaki engine, with hydrostat transmission). It was originally used as a finish mower, but I put a Little Buck loader on it and now use it only for moving mulch, manure and as a powered wheelbarrow to lift stuff I just don't want to, it works better without the deck for these tasks. I bought an older sears GT6000 as a dedicated finish mower.

My question is for field operations. I have a couple acres down by the creek that are wet most of the year and by the time it dries out to get a machine down there, the grass is 2'-3' tall! It is mostly grass now with weeds and no brush.
Is the 445 designed to pull a rough cut mower (I assume about 250-300 lbs of an older agrifab machine I got for cheap and fixed up) over a fairly flat field of about 2 acres sustained pulling? I would probably do about 1/2 acre sessions of about 30 minutes and take break. This would be for mowing the 2ft-3ft tall grass 1x-2x a year.

I just had it out to test the setup and ran it for about 30-40 minutes without issues, mostly flat ground. Not overheating. I had the throttle about 1/2 - 3/4 with the cruise control on going about 2-3 MPH.

Is this a reasonable use case for this? I have seen guys do plow days and I assume they are pulling a plow for at least an hour or more with garden tractors without issues. Is the transmission up to this? (I regularly change hydraulic fluid too).

Below is my setup...is this machine designed to handle this?

Thanks!