out side is better in my opinion, but there a lot who swear by wet box installations - if you are getting wetbox i would personally buy one rather than get one made - (airmar sell them)
If going external there is a lot of things to consider where to place it - making sure it does not get disturbed water flow from other hull fittings, prop wash etc and making sure you have the right (angle) fairing block so it is parallel with the sea floor. There are other debates such as using epoxy not sika to seal it - if your boat is trailered this wont be as important
Plenty of good info on the hull truth and youtube always good to follow a physical install if you have not done so before.

32 CC, nice! what brand?

I'm just about to go down this route with my cat. It's pretty much the best application for my boat ( try finding real estate on a cats bum for a transducer). Going for an 1kw Airmar mounted midships on the outer part of the hull. Good luck to you on your install.