Hi J.---I can't see any problems with having both boys and girls, providing you've set up ground rules for all of the kids, and their parents, like pick up times, etc. You didn't mention whether or not an overnight is involved. You could still hold the party and then have the boys all picked up by, say 11 pm.
When our now 17 year old started hanging out with friends, both boys and girls, we were most happy to have them all over to our house. Yes, it makes more work for you, but the great thing is that you know where your child is and what she is doing with her friends. It can help you to get to know those friends and be confident in their behavior once they are able to be by themselves. Your daughter will have her drivers license soon and then you might not see her or her friends as much.
It is so unfortunate that there are other parents out there that won't take the care that you would like with the kids, theirs and yours. I've heard from so many other parents about alcohol being allowed at graduation parties and other get togethers. At least when they are at your house, you can be sure that the kids activities match your expectations of them.
Encourage your husband to look at this as offering your daughter the opportunity to show you that she's been listening to your life lessons up to this point. It is our job to help them grow into good decision makers. Let her show you what she's learned.
Good luck and have fun at the birthday party. D.