I have an MX5400, which per the spec is just shy of 6 feet in overall width and equipped with an LA1065 loader, (so ~2300 lbs lift capacity at the pin, model number is lift capacity in kilograms).
The bucket I bought with the tractor is an L2296 heavy duty bucket, 6 feet wide. For reasons I don't understand I cannot find an online specification for that bucket at the moment. The bucket weighs approximately 400 lbs. The bucket is sized about right so that I can fill it with heavy gravel loads and the tractor will deal with it. It holds approximately 9 cubic feet.
That's great for gravel, not so much for bulkier/lighter materials. In fact my two cats can easily generate enough kitty litter to fill that bucket more quickly than you'd imagine.
I'm now shopping for the largest light materials bucket I can get away with for bulky but light items. I'm shopping for an 84 inch bucket, so it'll definitely be wider than the tractor by a foot. I could probably get away with an 96 inch bucket, even my dealer didn't say "don't do that" when I asked.
Most of the 84 inch super large capacity buckets I'm considering are 35 cubic feet or greater (struck capacity), and most of of them at that capacity weigh around 750 lbs.
Should work but I won't be putting gravel in it, I I'm sure even bark mulch would weigh too much (or challenge my tractor dynamics in some way) if I filled it with mulch.
I can't tell you how that's working yet, but I run these things by my dealer and he's certainly willing to sell me buckets wider than the tractor, and normally he's happy to tell me "don't do that" if my ideas are insane. Still, you really need to match the bucket to the use. I wouldn't attempt to do any digging or heavy materials in the big bucket, for me it's leaves and branches and light crap. Thing big 750 lb metal replacement for a tarp. Otherwise I'll be using my heavy duty bucket that is the width of the tractor.
I'll relay my experiences on this somewhere if/when I get the huge bucket. I think I'm going to pull the trigger on this:
Titan Attachments 84-inch High Capacity Skid Steer Bucket is designed to easily scoop and transport lighter material such as snow and other light loads.
www.palletforks.com
Because (a) it's available (though was on backorder until recently), and (b), it's cheap for the size and (c) I really want that 49 inch depth, though that will further challenge the lift capacity, that's way out there for a bucket. I haven't even seen any other buckets deeper than 39 inches. I know the bucket is going to look ridiculous on the tractor, but if it does what I want, great.
I'm definitely cautious, I have hilly terrain, and don't want to do anything that aggravates a tractor-tipping environment.