Maybe you could just have a friends shower. My sister in law just had a brunch with her friends, my mother-in-law and our other sister in law for her second shower. And my sister ended up having a shower for each of her three kids, #1 b.c it was #1, two years later #2 b/c it was boy, #3 b/c it had been 5 years since #2, but once again except for the first one it was mostly just friends and my mom and I no extented family.
I am actually hosting a second shower for one of my good friends in January, it has been over 5 years since she had her first baby so we are inviting her extented family too.
If you don't think that your extented family would approve then do it with out them, just have a simple get together with your friends.