hi , just because no one's responded yet ,here's my thoughts ;
Of course you can . After all a freelander is just a bigger ,more comfortable quad .
There are issues ; a 4ft wide flail ,behind a ~4ft wide quad makes sense . as opposed to the ~ 5ft wide land rover .
;fat tyres on the lighter quad make sense , as opposed to the skinnier tyres on the heavier l/r . ; manouevering on the quad would be easier , ;hedges etc could distress the l/r's bodywork . ;quad may be better suited to slopes .
I wonder if a flail is really required ? - bit of an animal ,compared with a rotary - bladed topper .
If it were me ,and i didn't want to buy a tractor and kit , i would consider a used domestic ride-on mower . Not so clever if the field is podded up by horses , or steep /wet . Would take about 1 hour per acre ,with a ~36 inch cut .
Remember ; 90's and 110's look good when a bit beat up , freelanders ,not so much .
hope this helps .