IDK where to get wide wheels, most guys just run 7 inch wide wheels with 10-12 inch wide tires.
For off roading skinny wheels are better IMO, its harder to bend them or jam stuff in the bead when the tire is a bunch wider than the rim.
I've had 12 wide tires on stock 7.5 wide rims a few times and my buds have them on aftermarket 7 inch wide rims without issue.
There's a few skeg type swamps by my place, we dont ride there much as once you make ruts the next guy is done.
The key is never spinning, just crawl in diff lock.
All the videos you see of guys ridng in skeg are assbackwards, they hit it wide open and try to skim/paddle across, it looks cool but doesnt work 9/10 times, I wish they'd stop posting them as new guys think thats how its done.
I was at a mud run last summer with a skeg hole off to the side of it. A bunch of us crawled right through it no problem then some young guys try to roost across full throttle and sunk. We crawled up to them, pulled them out and told em to just crawl, they pinned it again and sank so I rode around them and left lol.