I have mutant-wide feet and it's generally impossible to find comfortable shoes for any occasion. For the most part my only options in life are New Balance. I'm cycling a lot lately and would like to take advantage of cleats. So, does anybody actually manufacture 4E shoes? I'd rather not try stretching them out with mink oil/boiling water/wooden shoe stretchers and the pain from narrow shoes can be pretty excruciating. My google-fu is coming up with a few dozen forum discussions with no real solutions.
Sidi make a wide fitting version of their shoes.
I have a pair of Sidi's and they have been the best fitting, most comfortable shoes I've ever found. From their website:
Mega sizes are cut with more material throughout, and a larger-volume heelcup. Mega sizes roughly correspond to a EE/EEE width on the Brannock sizing scale.
Possibly still not wide enough for your needs but they're worth checking out.
Yes, D2 Shoes will make you a custom extra-wide shoe.
Good info on the D2 Shoes website. 41 sizes, 9 widths available. $975 price tag is tough, but looks like D2 Shoes will manufacture you an extra wide road or mountain shoe.
The widest off the shelf bicycle shoe I could find is the Shimano SH-M087GE Mountain Bike Shoes. The GE version is a wide version of the regular SH-M087G.
Once met a guy who had had his shattered foot "reconstructed" with screws, etc, and it was about half-again as wide as his other foot. He was riding in custom-reconstructed cycling shoes. He told me that the cobbler took two regular bike shoes, cut them apart, and sewed them back together as one.
As I recall (it's been maybe eight years), the shoes had cleats, probably SPDs.
(Of course, I have no idea who did the work for him, but probably an outfit that does "orthopedic" shoes.)
I found a cheap pair of shoes from Specialized that are awesome for wide feet. The Tahoe From Specialized. Note: this isn't a 'competitive' shoe; it's classified as recreational. I ride a hybrid for fitness, and I wear 10.5 US 4E New Balances when I buy athletic shoes. I paid $85 from a retailer but I think you can get them cheaper.
The shoe works because of the construction. They're built like Keen or Merrell sandals, meaning they wrap around your foot in a basket-like construction. It's not a sandal though, in that the sides of the shoe have strips of leather and nylon that flex around the toe box.(don't know if I'm using the right terms) Again, I'm a fitness rider, and I need a versatile shoe for commutes and long rides. And I've been wearing them on long rides for two weeks without any pain. These have a pop-out section on the forefoot to accomodate a clip if you want to install one.
You may also want to check out custom=made shoes from BONT. They aren't cheap though!
It's also possible, if you have the tools and the inclination, to make your own from a pair of non-cycling shoes that already fit correctly. Ideally these should have a flattish outsole (so they don't catch on the pedals) which is also thick enough to recess the cleats.
You'll still ideally want the stiff insole from a cycling shoe (as here) to spread the pressure from the plate the cleats bolt onto. So, you need a donor cycling shoe whose sole isn't too narrow, but at least it doesn't need to fit around your feet for this to work.