Don’t worry about the cabover hanging too far over your cab with an extended cab truck. We have a Bigfoot with a long N-S type cabover on an extended cab Ford F350 and it does not bother us a bit – comes to just about the front of the windshield. Does not obstruct views of canyon walls.
Big advantage of the extended cab: it has a shorter wheelbase – easier turning in tight spots in parking lots and for off road travel it is easier navigating twisty dirt roads and turning around at dead ends. This was pointed out by Mello Mike in a long forgotten blog post or article that I took to heart.
We have a lot of stuff stored in the extended cab (I took out the back seat). Have never regretted it. In fact – we are very glad we do not have a crew cab.
The other extended cab advantage: it is lighter so more payload.
Now if you have kids, go with the the crew cab for obvious reasons.