I think the tone of the replies just reflects how the question was couched, which is making this all seem worse than it is..
Anything you can drive over with a mid mount mower deck will not faze ANY bush hog. If OP hasnt bent any MMM blades or bent/damaged any spindles, theres no cutting of 3” anything going on (yet) which is fine!!
I think if the question was ‘is any 4ft bush hog much tougher than any other?’ the tone of discussion might be a little less YOURE GONNA KILL YOUR TRACTOR but the same basic info would have come across. People are responding to words, but noone has seen you do what youre doing to 100% tailor their suggestions, we’re just.. swinging at it.
If you have ssqa on the BX you might consider getting a small stump bucket for these pine popping operations. Or, since youre saying these things come out pretty easy, might even consider a set of pallet forks if you had any other need for them. They will pry up stuff AND carry it, and it would take a lot for a bx to hurt a class1 fork even doing unauthorized tasks (digging). Just throwing stuff out there.