Well generally its a superb idea and i would surely be part of a mod since the Osmanic armys lured twice at my homecitys gates, the turkish wars where practically an "equal" to the greek-persian wars. However the fighting in Moldawia was not that important, i would rather set the area into Austria-Hungary in the 1520s. In that time Hungary was finally occupied after 70 years of struggle. Under Suleiman I. 1520-1566 the osmanic empire was at its height, and their expansion in europe was stopped at vienna, although it was more the fact that there was no infra structure in hungary so the osmnaic army was not able to bring in their siege canons. The winter came pretty early that year so they had to withdraw.
On wikipedia i did not even find a polish - osmanic war in that area, although it is clear there was some decent fight going on since the Polish kingdom was a direct neighbour to the osmanic controlled areas in moldavia, "siebenbürgen", etc.
So if a mod would take place in that time, the area would stretch from siebenbürgen (western ukraine) or even moldavia to eastern austria, although austria was still a small "state" at that time and still no kingdom itself. The longer the Osmanic wars lasted (totally 300 years) the more important became austria and russia of course, although in the 16 th century they did not even have a border with the osmanic empire yet so they would not take place here.
2nd sugestion:
1683 The 2nd siege of vienna, while the first one broke after 19 days due to lack of supplys and early winter, there where up to 300.000 men standing at the gates only defended by about 12000 men. The siege was lifted after a long bloody battle by an holy alliance initiated by the pope, led by the polish king Jan Sobieski III with 70000 men and his legendary hussaria cavalry cabable to attack and break pike formations from the front! The time around the siege would be a superb mod, osmanic warbands plundering the sorounding villages, killing or enslaving the inhabitants, almost as M&B is right now
I have found a very good map of euroe of that time, all the events i have described above are shown on the map with date.
http://members.chello.at/h.baumgartlinger/europe.jpgPs: PrinceScamp you where right about the canons in both