Zentmeister
Look, being excommunicated is not just "boohoo people think I'm stinky"... It means people can take your title without repercussions and are even rewarded for doing such. Any enemy will be able to have complete impunity to get rid of him and even his trade deals can be outright canceled or they can take advantage of him as they see fit. You have less than 2000 men and think you are strong at this age? Muskets have limits and so do cannons... You would need at the very least 40,000 to be able to face these repercussions.
Just before you do it wrong, remember that in those times the Itallic peninsula was divided in the Reign of Naples (belonging to the Aragon Crown), the Pontificial States, and a lot of little kingdoms in the north of the peninsula, between the Pontificial States the Holy Roman Germanic Empire and France.