I know where you were talking about. It's the same place everyone else is when they say up front.
The V on the Z-7 trailer is too narrow to put a cage like you are saying, and where the 2 sides of the V come together on top, where you are saying to put it horizontally, there are 2 trailer lights on the top of each side of the V, and the tongue jack is also there. There is NO WAY to put a 14" tire there unless you offset it over 1/2 the tire diameter to the drivers side of the boat.
The pic really doesn't show just how little clearance there is in that area under the hull.
Trust me, I wish there was a way to mount it there. The trailer is only about 14" wide at that point, and the tire would require a minimum of 25" of clearance to mount it there. With the tongue jack being mounted to one side of the trailer, I only have 14" of clearance to play with...just not enough.
Another thing to consider, is by mounting the tire that far forward, you will increase the tongue weight a lot. While that won't matter to the dually in the pic, my Cherokee wouldn't like it at all. Heck, I'm not even sure it will like the tongue weight as it is now.
I tried to lift the tongue at the store, and it is a lot more than I was told or expected. I didn't really grunt to lift it, but I didn't move it either, and I'm not sure I can by myself. And I ain't no weak little guy either. I still have to determine what it is. If it's more than 300 lbs, and it may well be, I won't be able to use any of my other vehicles to tow it.
NO offense taken by your suggestions at all, you're just trying to help, and I appreciate that.