</font><font color="blue" class="small">( a mid-mount might be better suited )</font>
That's the reason they make both kinds; I prefer the other, but lots of folks prefer the mid-mount. Either one will do the job.
</font><font color="blue" class="small">( I don't know how much a brush hog can handle )</font>
It depends on which one you buy. Most of the manufacturers make light, medium, and heavy duty models. I've actually seen a light duty brush hog (rated for 1" saplings), on a 29hp tractor, cut down little trees in excess of 2" diameter with no apparent damage. Of course, if you buy a heavy duty model, you can cut bigger stuff, but may need more tractor horsepower. I'm not recommending any particular brand (there are lots of good ones), but just as one example, Bush Hog has a heavy duty 6' one (model 406) that's rated to cut 4" saplings, has a gear box rated to withstand 125hp, but recommends a minimum of 45hp.
Now it also depends on what you call "clearing". A brush hog will cut them, but leave a little stump. So I don't know whether you want to get rid of those, too, or not. Brush hogs have relatively dull blades (compared to lawnmower blades) so they tend to shatter the little stumps so that does frequently make them decompose quicker, but for awhile after cutting, they might damage a tire if you run over them.