How many of those 11 acres do you plan to mow? How big are the saplings?
If you went DR, my guess is you’d be looking at the PRO-44, maybe the XL44 due to how tall the grass is and the saplings. They are quite spendy - north of $3k new and they aren’t ideal.
An acre is 43,560 square feet and with a 44" inch deck at 3 MPH (you wont get going much faster than that in thick, tall grass with saplings) and 100% efficiency, you could do about 57,000 square feet an hour. But, the truth is your efficiency will probably be closer to 70-80% when accounting for turns, overlap and bogging down in the thick/tall stuff - don’t believe the marketing for 2 acres an hour unless you’re mowing a foot of grass.
The other part is that ATV’s have a tendency to heat up quickly when you’re moving slowly and towing for long periods of time. There is a real possibility you could burn up your wheeler over time.
The point is, you might be better off finding someone to hire or rent some equipment. You might end up paying them $80/hr, but I can cover about 3-4+ acres an hour with my 60 inch bush hog going 7-10 MPH with my JD 3520. You’ll probably find that the amount you spend to pay someone for two mows a year for 5 years is less than you’d lose in the depreciation on that bush hog before you could afford your own tractor - then it’s not your butt out there getting baked or your wheeler getting fried.
The pull behinds aren’t bad, but you just need to know that they weren’t really meant for clearing 11 acres of overgrown pasture several times a year. You might even make it work, but just thought I’d share some of the math I did when going through the same questions.
Good luck!