SCUT = sub compact utility tractors = overgrown riding lawn mowers on steroids, with FEL and cat 1 -3pt hitch. the JD that you linked to.
there be some "stand on mowers" = zero turn but you stand on the back. maybe keep your face and arms from being nailed by branches, and keep your eyes up above, so you can see maybe were you are at within the field of trees.
there also be "power-trac" = all attachments fit on the front
and then "skidsteers" = more for construction normally, but folks use them on the farm. top MPH most likely slower than other stuff
there also be ATV / UTV pull mowers with there own engines on them. either get finishing mower to rotatory mower (bush hog) pending on pull mower some have "off set" ability to swing them out to the side to perhaps run them under low hanging branches. there be better name for the "off set" but i do not remember it right off.
there be "fence line / post mowers" if fence itself is high enough above ground, the fence line mowers swing out and go around posts with some guides. not sure how much of a beating smaller tree saplings would take as in a beating or get mowed down due to not strong enough.
double check your finishing mower decks. some only discharge to the side, some both sides, while others send all cut grass to the back. more than likely 3pt hitch finishing mowers to pull behind (trail type) mowers for ATV/UTV more likely be default have decks that send everything out the back. pending on the back, you might have a shield you can replace with chains or like. so you end up with less "wind rows" ((clumps of grass)) i bring this up due to mowing around smaller saplings and burying them under cut grass with a deck that sends clippings out the side.
rotatory mowers more likely always send stuff out the back, and more likely rough/tough handling. some folks get more of a finishing mower blade set for them. and keep the blades sharper for finishing mower like cut. and use them to cut the regular lawn.
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what acreage are you looking at mowing?
is it purely mowing? or other stuff you want to do with unit?
you already have a TLB (tractor loader backhoe) larger unit. so questioning what you want else to do beside mow. pending on a mount of mowing, it might be better just getting a deducted mowing machine, so you are not beating up a machine that you rarly ever use to do some misc things.
you noted 48" but then jumped up to 54" deck. is there a specific width that you truly need to stay within? due to distance between trees? which is?
