You seem to have a huge wagering with those sportsbooks that you've mentioned. And with that, I think that there are usually limits that they'll be flagging you down even before reaching certain amounts.
But if that's what it is and you're telling the truth, someone might be curious to ask for proof but if you think that you're not obliged in doing so, that's fine.
If you've got the same experience with those, you may check and try betcoin but read their terms about such limits.
with such amount that we are talking here, high likely that the casino will ask for kyc from him. and i believe he is ready for that. because most licensed casinos will ask such proof of identity and source of funds if he will channeling that big amount to the casino. i don't think any casino or bookie will miss such high roller in their site.
the OP should stick to bookie/s which are known respectable sites in the forum, and with active support. it is always best to have someone that you can reach out in case of trouble with your account or any issue encountered when you are playing inside the site.
I also Agree with what you say , it is always good to do things in the most Correct way, just like you, I think that the things that can be done in the countries that OP says have to be in the Best and Most trustworthy members of the forum, because the Problem will Always lie in the KYC , and it is very likely that the players who accept this deal will want not to do the KYC, and I understand them, it is something that is not very pleasant, and that few would want to do, personally I have always thought that the people who do the KYC and who can do much more than this , because they are also limited, you can comply with the KYC, but if you manage to win big, then they Will ask you for a Much more radical KYC, much more demanding and this is something that the esuga adds, then the KYC in the casinos as well as the service they want to offer must also be Presented as an option that must be had in case the person has to play with a Personalized account , now if the Deposit of Funds goes to a single account, because things change, everything Becomes different and basically the only thing one can focus on is that they fully trust the service that the OP is offering.
When it Comes to how to Offer the Service , it would be nice if You could show Your Results, the people who are probably already working with you doing this, this will Give you the best chance of doing things right, of course I say that from the point of View of being a demanding and clearly concerned client because you have to be very careful when you do things with Money , I could say that when it comes to money things are more delicate, and everything has to be done in Detail , and everything has to be clear , because for minimal things that involve money, there have been many problems and that is something that you cannot afford to do Or allow, that is why I am very careful about those Things, you Should Always have a lot of Moderation.