Hi Wolfgang80,
The type of hand crafting you are looking for tends to be more costly and found in more premium mattresses and your budget may not be enough but there are some manufacturers in the Los Angeles area listed in post #2 here that may be helpful and who may be able to make you something that is suitable. There is also a San Diego list in post #2 here.
I don’t think the size is nearly as difficult an issue as finding the type of cover that you are looking for which is a more specialized construction.
Phoenix