Tough questions. I urge you to look through some of the threads on this forum devoted to coming out vs. not coming out. I'm in a somewhat similar situation: We live in a very conservative area, we both agree to keep our poly arrangement very closeted, only a few friends know, and I'm a little shy and introverted. You've already found one of the ways to deal with this: use the internet to find like-minded individuals to converse with.
I enjoy getting together socially with some of our close friends who are in the loop and occassionally inviting others who aren't. The new friends get a gentle, non-threatening look at our lifestyle and can see how fun it can be. So that is one way to handle things.
I've found CL to actually be a good resource for finding people but remaining somewhat anonymous. There's also swingers' parties you can attend in some of the larger cities. Swingers aren't really into polyamory or open relationships normally, but you'd be surprised how many open-minded people you'll meet at these parties.
I hope at least some of this helps.