Look at this this way - the front wheels have the correct offset, dish, to center the weight over the inner and outer wheel bearings. Reverse the front wheels to increase track width and you have a much greater load on the outer wheel bearing than what it was designed for. Even the 2wd Yanmars occasionally break a spindle. I assume the 4wd's could too. You don't want that spindle to snap on the downhill side of a slope, or while driving with an unbalanced load in the loader bucket raised up a little too high. Don't do it.
And an unrelated consideration re geometry: Since there are no front springs, there is no resistance to rollover until the chassis comes down to meet the front axle. I think by that time you are tilted so steep you have a rear wheel far off the ground, meaning you no longer have engine compression to slow you down - so you are out of control rolling forward as well as tipping over, and will be lucky if it doesn't kill you. Widening the front track won't reduce how far the tractor tips. The only solution to this risk is to operate cautiously so you never get in such a desperate situation.
