Spaying and neutering outdoor cats?

I recently moved to a new place. Along with the place came two cute kittens. So they are now my kitties! I'm excited as I haven't had a cat in 4 years since my Morris ped away...Chester is an orange tabby and Lily has flame-point siamese markings. They both came from a farm and are outdoor kitties. Problem...Lil needs spayed and Chester neutered. How do I do this without bringing them inside for recovery? My boyfriend is allergic to cats and having them indoors is a no-no. His allergies still act up with them around but not nearly as bad since they're outside. I'm waiting until after winter to do this also. Any help?