On few occasions when I get to this step on most fiat online casinos around my country, what I often used as source of funds could range from statement of account from banks.
My question is can we use crypto wallet with long history of transactions and possibly a sign message be used as source of funds requirements for online crypto casinos?
You shouldn't be asking us, what is the name of this online casino? Is it available on this forum? Forward this same question to them and wait for their reply, if the casino is crypto friendly more than just payment option I think it is not a bad idea to accept your address as the source of past funds because I have seen one who did the same.
By the way, do you have a problem using your bank account statement? I think this is very easy too, you can download your bank statement through your bank app and it will get sent into your email address in .PDF style, it is a gambling platform though not a centralised exchange so I think you should be fine.
The main goal on the casino end is making sure that the name on your ID is the same on your bank account, this is another reason why they might not accept a crypto wallet address, you have no choice but to follow whatever they ask of you.