I have a
L3200 with R4s & loaded rears. The R4s are non adjustable so permanently have a track of 60". I generally like the size, but it FEELS a bit tippy at times inducing significant pucker factor. However as a practical matter it's got better stability than it feels like.
However I've pushed mine way past the pucker factor feeling safely. Mowing some ditches I estimate I was heeled over 35+ degrees or so, maybe even over 40. In 2wd inching along mowing with the bucket & loader really low. Finally I stopped moving, but looking at the high side I could still see the wheel spinning. Put it in 4wd, backed out & abandoned that ditch. It felt bad, but was still surprisingly stable, even when I lost traction on the high side. I'm sure wider would have felt better, but I don't think it would have helped to much.
The closest I've come to rollover was lifting big square bales with SSQA pallet forks. Hit a tiny dip in on a very slight hill. Despite having my rotary cutter on for ballast I think I was briefly balancing on the front axle pivot before the bale rolled off.
Generally I keep it in 2wd unless I'm doing loader work or ground engagement stuff so I have plan B a lever away if I get stuck.
The main reason I was thinking about wheel spacers was so I could fit rear chains (would otherwise hit fender brackets). I'm going to be selling my machine & getting a cabbed unit. Probably a
L4060 which is wider, but was really tempted by a JD 3039r, which has the same 60" track ($7-10k more than the slightly bigger Kubota though, pushing it out of contention).