I would keep the smoker at about 375-300 maybe alittle higher and take the birds to 165-170 in the breast. I wouldn't think that they would take longer then a hour and a half maybe longer but they are pretty small. Cause we here really cook be temp not by time.
Best advice is to track what you do smoke for temps and times as this seems to be one of the toughest questions posed here on the forum.
Give yourself plenty of time as you can keep your hens warm by wrapping and placing in a cooler for quite a while.
My smoker would only go up to 275 degrees.
I played it conservative.
The process took 2 hrs. and 50 min. I pulled it out at 178 degrees.
I smoked it for 2 hrs. at 225, it was then at 170 degrees. I bumped it up to 250 for 25 minutes, and it took it up to 175,,,I then bumped it up some more to 275,,,,and finally gave up,,kids where getting hungry.
It was 0 degrees outside !!