On a 5.0 theres a couple kits that use the tensioner as an idler to maintain the serp belt. Or a dozen country boy ways to do it. I just makd a home made idler bracket and used a spare idler for the belt, in the former ps pump location.
Have not done this to a 2.3, but the idea is the same.
There should be some 2.3 non ps accessory bracket setups in junkyards, because many of the early Mustangs with manual steering were 2.3 cars. They are probably v belt setups though.