Alternator bracket pic request

The alternator belt should come off of the water pump at almost a 90. Not enough wrap on the pump and it may slip? In your last picture it looks like all three pulley's are in a row.

There are times if you see someone jump off a cliff. You should look over the edge before you follow to make sure there is water down below.

Making the belt to tight to compensate slip may ruin the bearing in the alternator.

The AC alternator pulley would have worked perfect. I see your way is easy but I would be concerned about belt slip . V-belts should always have a at least 1/4 turn of wrap on any pulley.
I guess you'll see how long the belt lasts if it stays on . It may work if you keep the RPM's down and replace the manual fan with and electric one. Good luck.