There is only one male dancer in the Western Hemisphere who is a professional performer and can properly be characterized as "big" - Larry Goldhuber, and he must have his dancwear specially made.
Capezio also makes XXL tights, possibly XXXL also, though I'm not sure of that. The XXL tights are footed and only come in nylon. I personally found them quite uncomfortable, but on the plus side, they are probably the least expensive men's tights on the market.
M. Stevens footed Milliskin tights, in XL, will hold up to a 38" waist and 38" inseam.
There is another resource for big and tall men's tights - the shops and websites that sell historical costumes, such as the ones worn by the people at Renaissance fairs and in period musical groups. These tights are more realistically sized and can probably be used as dancewear.
Shoes - a/k/a ballet slippers - should not be a problem. One essential item of the ballet kit that is not, so far as I know, available off the shelf for waists in excess of 38" is the dancebelt. If you are much above this size you will, like the above-referenced Mr. Goldhuber, very probably have to have dancebelts made to order. For heaven's sake, don't try to wear a dancebelt that is too small, unless you are already a eunuch.
Bal-Togs leggings may be ordered from riversedgedancewear.com. (A word to the wise - I hope you're not in a hurry. Tights and so forth in exceptional sizes take at least a month for delivery.)
It's been so long since I ordered Capezio tights, I don't know the address of any website that sells the XXL etc. tights. But just plug "capezio men's tights" into your search engine of choice, and you should find what you're looking for.
The same is true of historical costumes, only search for "renaissance dancewear".
I order M. Stevens tights from backbaydancewear.com. The site is not very useful, but you will be better served if you simply call them directly, at the toll-free number referenced on their site. The CSR who answers should be able to tell you right off the bat if they have your size.
Hope this is useful.
Bill
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