What's the draft on an I/O or outboard? I think the draft on most inboards is about two feet, more for an I/O or outboard, right? Draft is depth, below the waterline, of the lowest part of the boat, while the boat is at rest. That last part is very important, manufactures list the draft when the boat is at rest.
The spec sheet on a new SeaRay 195 sport is 34 inches with the outdrive down and 17 with the outdrive up. http://www.searay.com/boat_graphics/electronic_brochure/company13008/53997_f.pdf
The draft on a new SeaRay 185 sport outboard is 30 with the drive in the water and 12 with the engine up. http://www.searay.com/boat_graphics/electronic_brochure/company13008/53995_f.pdf
The draft on a Malibu VLX is 24 inches. http://www.malibuboats.com/w21xti.aspx
The draft on the Mighty Centurion Lighting (my boat) is 27 inches.
Both outboard and I/Os will have bow rise, when that happens the bow goes up – of course, but the transom (and outdrive) goes down, deeper than the at-rest-draft. When you’re on plane at fast speeds your draft will be much less than at rest. However, at wakeboarding speeds, you’re not quite on plane, and if you have a lot of ballast you might be deeper still.
An inboard does not have as much bow rise and since the prop is further forward and since the prop pushes the boat up and out of the water, does not go deeper in to the water when starting. Your draft while wakeboarding will be less on an inboard.
Now I know you're not looking at new boats, I just used these as a point of reference. I don't think an outboard is going to help you with shallow water. If you are really running in two feet of water, you should consider sticking with a jet type boat and try wakeskating. Bigger wakes need deeper water, I think 5 feet is a minimum, 10 feet or more depth is much better.