Iceman's recipe for the custard is fine, except for a Monte Cristo I'd leave out the sweetener. I'm not a big fan of heavily sweetened components of a savory dish, and the raspberry jam brings more than enough sweetness to the table.
I suspect you're right about mixing turkey with the ham. But there ain't no food police visiting your kitchen, so if that's what you like, go for it. If you're concerned about authenticity, leave it out, cuz the original was just a ham & cheese sammy.
KK, I'd use a nice gruyere. If you like a more earthy flavor, try making one with taleggio, or a combination of the two.
I agree with both of you re: patty melts. There is one danger, though. If we promote them too strongly the folks at Weight Watchers, and Jenny Craig, and Nutra System will come gunning for us.