I think, you are over thinking this. If someone, especially a friend, wants to buy you a gift, they will buy you a gift regardless of whether or not they have been invited to a shower. If my shower was 3 hours away, and my friends were not invited i'm pretty sure they would still know about my registry and get me something. Acquaintances are a different story. On the flip side, if you want to get together with your girlfriends for lunch, than do exactly that.Dont "hold a luncheon celebration" for yourself. This is cheesy. I feel like you are more preoccupied with how to get gifts from them than anything else. If they are actual friends this shouldn't be a concern.
Also, FWIW, if any of my girlfriends had a shower and I wasn't invited, 3 hours away or not, I would be highly insulted. So are these ladies really your friends?