Easy gentlemen - there's common ground to be found here.
A 61 year old tractor was/is built substantially beefier that modern SCUTs/CUTs are today. Most of them used pretty much the same size/strength components that modern industrial equipment has - therefore it can probably do things that we newer tractor owners shouldn't / can't do.
For the education of the OP and others, this is what 4570Man is talking about and even if you don't bend / break cylinders you can still damage other components of your FEL.
(I know because before I learned I shouldn't be doing this I put a couple of kinks in the "Boom Linkages" on our KL130 loader (and I'm not the only one
https://www.tractorbynet.com/forums/parts-repairs/371830-kioti-kl130-loader-c-bracket.html)
Now back to the original question
In your case the chance of a sharp stump that will get a tractor tire with material that small a diameter is small but still possible. The greater concern to me would be any ATV tires if you plan to ride across this path when you're done.
If you're just clearing for a walking path then hook up the rotary cutter and go at it.
If I knew FOR SURE there was nothing in the way I'd just mow "normally" (but I was taught by a man who's motto was "If the tractor can run over it, the mower will cut it"

)
Otherwise, I would back in with the cutter raised and running just to the depth of the cutter and lower it slowly mowing to ground level then raise, back up, and repeat.
I've done acres of blackberry and briers along with scrubby Fir and Pine like this over the years with no issues.
If you're planning to make this an ATV access trail (or you want no stumps & stobs because you're clumsy like me and will trip over them)
My advice would be to bite the bullet and get the Piranha Tooth Bar (PTB). That way you can push, shear, and grub till you're hearts content & have a much better path going into your site.
There are others who would suggest a Ratchet Rake (RR) instead. I have no hands on experience with it but from reading here I have no doubts that it would not work as well. Just given the different ways the RR and PTB mount to the bucket and the fact that you can't dig with the RR attached, I opted for the PTB instead (and I love it, next to the grapple it's my second favorite attachment).
Obviously there's more than one way to skin a cat (or clear some undergrowth) so best of luck whatever you chose, just be safe.