Just my thoughts!
I don't think this is a scope of practice issue, rather an approach issue.
What is causing the ulcer? Ischaemia, venous insufficiency, malignancy, warfarin therapy? Without identifying the cause of the ulcer, your dressing choice will remain irrational.
I this was my patient, I would try to identify the cause of the ulcer via Doppler ABPI and a good medical history and then contact the GP suggesting a treatment plan including onward referral to e.g. nurses/vascular surgeon/dermatology. I would then re-dress itas per my 'diagnosis'.
What I would say is that betadine solution is a poor choice in commparison to inadine dressings and that a dressing that prevents further bacterial infection by being less 'porous' such as any foam dressing, would be better than sterile gauze, but it really is impossible to decide what your dressing should be unless you know what is causing the wound and what you are trying to acheive.
Scope of practice-wise, I think it is fine to make suggestions about further care of this wound to the appropriate bodies, but it would be remiss to treat this in isolation.
If you're looking for info on dressings,
www.worldwidewounds.com has about as much info as you'll ever need!
Hope this helps!?