You could.

Typically you wouldn't want to use a mixture like that (5% acetic acid). Even though it doesn't form an azeotrope, acetic acid is volatile enough and close enough to the b.p. of water that it will still work. (its hard to concentrate acetic acid by boiling or distillation, you need a very tall column).

Though, It would be much easier to use something like ethanol in the soxhlet. Make a crude alcoholic extract which you can distill off the ethanol, then do the A/B on that crude extract.

It is extremely effective in reducing the material you have to work with, and alcoholic extracts of natural products in a soxhlet will almost always give you quantitative yields.

I don't know about acetic acid, it may work just as well but could take a lot longer.