The other product I use from time to time if your box do have room I used Polairs connetor block they have one for small size but again just watch out the room in the box otherwise you will get it crowed pretty bad.
Jes., If you have 4X4 box it may be ok depending on the type of recetpale you are using and size of mudring you need to get it fit in.
Pas de problme,il marche n'est-ce pas?"(No problem, it works doesn't it?)
They do make several sizes of traditional split-bolt connectors listed for copper to aluminum connection. I don't have any specifics on them as far as minimum and maximum run conductor sizes go though.