Ah, I wouldn't sweat getting a smoker that's larger than you think you'll need...you'll be glad you have all that extra space, because once you really get rolling, you'll want to load it up and stock up the freezer to make it worth your effort and time.
No damper? Shouldn't be too much reason for concern with a vertical propane smoker. I run my exhaust vents full open most all the time. Let us know if you have any questions on getting proper/adequate smoke from it, any temp control issues, etc. Just remember, when it comes to smoke, less is more. If the smoke comes on heavy and white at first, that's normal...it should settle into a thin blue smoke within 5-10 minutes. If it stays heavy for a long time, then you need to make some changes. Usually too much chip or chunk used at once, or, too much heat/air getting to the smoke wood. Don't soak your smoke wood...toss it in dry.
Eric
