Well, given the ratio of beach to inland hunting you plan, this automatically pushes you towards the Excal. The ExpII will do fine on the beach up to the waterline (and up to submerged coil) but as you know from frequenting the beach, the salt gets in the air and goes everywhere it wants to go. Additionally it is hdyroscopic which means it has an affinity for water tending to keep things that it covers moist.
Moisture and salt is very bad mojo indeed for electronics, and I haven't a clue how well the ExpII case is sealed against this. You might want to call Minelab USA at 702-891-8809 and ask them how well the ExpII fares in salt air for extended periods. If they say it's good to go, then I'd say the ExpII is the best choice.
If they say there might be some concern over time, then the Excal is the clear choice. If this ends up being the case, your entire hunting scenario can change anytime you want, allowing you to enter the surf, dive, or just generally ignore the enviroment in which you hunt without risking damage. Of course a good rinse and cleaning is still a good idea, but the thing is designed for environments that are guaranteed to kill a lesser machine.
As you ponder your decision, keep in mind how many folks DON'T have water capable machines, and the surf zone is strictly off limits to most of them. This COULD mean more finds for you, but of course nothing is cast in concrete when hunting.
At very slightly over 4lbs with the 8" coil, the Excal is a bit heavy, but the ExpII is no flyweight either (I don't have the exact figure).
So my highest recommendation is to give Minelab a call and see what they say about the ExpII in salt air first, then make your decision from there.
If you do call, it would be great if you could report back here so other can benefit from the info.
Best of luck,
DAS
