Push Nuts: How to apply when cannot push straight on?

Push Nuts (example) are fairly easy to apply when just pushing onto the shaft.

But I have to apply one through a smallish opening on the transaxle of a lawn tractor. The clearance is only about 2.5".

My best thought so far is to use something like funtac putty to stick the Push Nut onto a box end of a wrench just slightly bigger than the shaft. Then use some long heavy duty screw drivers or wrenches to force the box end down and hopefully applying the push nut onto the shaft correctly.

**Anyone have any better ideas or other suggestions? **or just other things to try?

Freaking Craftsman has gone to shit and this is the third failure on a 3 year old tractor for a part that should never fail. I actually had welds fail on the mower deck. *

Your idea will work.
I’d just tape it to the socket, put it in an extension, and tap it with a mallet.