These are my suggestions, Sean.
1. Look after your own recovery.
2. If you are interested in starting a GA group in your area, ask one or two members from your previous GA group to go with you. Advertise the Meeting in local GP surgeries, churches and casinos. Just put up a small notice. (CGs will not be affected by flyers. A small notice, well placed will be far more effective)
3. Don’t try to rescue people. (I did that for years. It doesn’t work. Every person needs to ask for help in his/her own time. Neither you nor I can take one step for another person)
4. Introducing a gambler to a well established AA group sounds sensible. Like GA, AA is a Spiritual programme. The fundamental 12 Steps can be adapted to all types of addiction.
5. If you get even one other gambler to attend a GA meeting, use the official GA literature. You will need to get consent from GA headquarters to to this, as far as I know. Keep it anonymous. The threat of being “found out” is what stops most people going to GA. There are GA Conventions and Awareness Groups available worldwide . Anyone can attend those or if interested people are free to attend Open Groups.
These are just my thoughts, Others might have better/different suggestions. In my experience , when I was acting under the guise of helping others, I was deflecting from my own recovery.
God bless your efforts!