We do. Here are the 4x8 cases we have in stock.
https://jbcases.com/stock-cases.html?dir=asc&order=qty&size=53
We can also modify a 4x8 to be a 5x10 but the padding is reduced considerably.
You will find that pretty much everything about our cases is of a much higher quality than any other models in the same price class. And if not send it back for a full refund. If you decide to keep it you have a lifetime warranty.
We also have an online designer where you can build your own case with over a million combinations. The cost to do that is typically $10-20 more than ordering stock in the same colors unless you start adding names, logos, shapes, and more accessories.
Please take a look and see if we can't satisfy your need.
John Barton
www.jbcases.com