First investment should definately be a good board, bindings and rope, as well as a few videos to learn good edging and all the basic's. If he's talked you into that already then get 600lb sacks for the front and rear of the boat to start. You can get darn good wakes out of I/O's and outboards since you can use the trim to help get a clean ramp on the wake. It will take most riders as far as we can get time for.
A tower or pylon will definately help. There is no structural or technical reason you could not mount a tower at the very back or front of a boat. It's more an function and appearance issue.
If you need a tower that folds down the towers that fold to the back would not work so well but there are towers that fold to the front that could still fold down. The look would be different and the rope would not be as high. Check out a link to all the tower companies at
http://www.worldwakeboardcouncil.com/links.html There are also Pylons that may be an option.