I guess you would need to have a mulch plug in the back of the mower Norm or make up a rear blade cowl so you don't loose air flow to throw the grass out ,then the base would need to be reinforced on the side where you cut the side discharge position out . The air flow is wrong with a rear discharge to be used as a side discharge as the rear discharge opens up mostly at the back where the side discharge opens up mostly at the side discharge port.
The rear side discharge sheet metal cover didn't seem to take off. I think people like the look of the Utility.
Pity we can't get 100 Utility bases stamped out at a cheap price.