Indeed. Asking their support will be the best thing that we can do to know if they allow their member to use VPN or not, as some gambling sites will not have a problem with that.
In OP's article.
It is written what casinos do allow VPNs and what were those that he has listed that don't allow it. Asking the support is also fine to know just to be sure and for the sake of your safety. But most of the time, they're indicating it on their support page, faq or terms and agreement.
Using the same IP for our region will cover that and I think that will not give us trouble when playing gambling.
Be careful also about the same IP. Some casinos won't allow that.