Years ago, after a bike-crash I damaged my lower back. In my DAF YA126, I had to push with all I had on the clutch pedal.
This was a very heavy issue. (after bike-crash). so we installed a clutch-booster, (looks and acts like to an brake-booster) this made it very easy to use the clutch. (even my daughter then 6 years pushed with ease)
All the items are available in the Cherokee (except for the booster)

I looked in to the manual, but swapping from stick to auto, you need for sure rewire a lot, and need an extra computer for the tranny. (neutral switch, and other tranny sensor information)

asking to my friends, they all believe that it would be easy-er to do a clutch job than the tranny swap.

I also believe that your present gearbox, will act better off-road than an automatic, because you have more control to your self when shifting up or down.. But that is my opinion..

Thomass