Nice build.I carry a spare with me. It'll eventually happen. Florida mud has killed a couple Ranger alternators.
I play in deep mud like you, and have a similar type of build. I also carry a spare alternator, but have yet to need it. I think the problem isn't so much about being in deep mud, or water, but how well set up your truck is, and how you approach the mud. Shrockorks (or other) skid plates go a long way in blocking direct splash to the alternator, and approaching/entering at a proper pace as well. I've been deep enough to bring water/mud in the cab, and never even had a warning light.
Tagging @halligan1201 as a second answer to their question.