Wow, 50 acres/5 ft mower! I wouldn\'t want the job
At least you will be bonded with your machine after that!
A lot of variables you didn't mention: How tall is the stuff? How many obstacles like rocks/trees/gulleys?
I'd not want to do that job with what you said, if for no other reason than boredom.
How about renting a 10 ft mower if your tractor can pull it? Should cut your time in half. Or even rent a different tractor and mower to do it faster, if your tractor can't pull it.
Fifty Acres is a BIG area, when you go back/forth five feet at a time, and counting some overlap, you'll be looking at 4.5 feet or so.
An acre is 8.25 ft wide x 1 mile long Fifty acres is 412 ft wide x 1 mile long. Figuring 4.5 ft each trip, you're looking at 92 passes to cut it.
If you can do it at 4 MPH, you're making 4 passes each hour, so your seat time would be 23 hours (ok, I'm rounding here) assuming no obstacles and flat ground and no time for each of those 92 turns to go the other way.
Even if you bumped it to 6MPH (doubtful), you'd be looking at 15 Hrs. Bump up to a 10 ft mower (figuring 9.5 ft each pass), now you can do it 11 Hrs @ 4MPH (same assumptions, no obstacles).
I used to plow 1/4 sections of ground as a farm kid. Round and Round with the plow not much wider than the tractor. Round and Round, over and over, 3 MPH. Long Days! Boring!
My opinion is you need more power! Best wishes.
Ron (loving excel for the math, hope it's right as I'm not awake yet, your mileage may vary, but not by enough to want me to mow that acreage!)