The theme idea is fine since there are enough active members that frequent this forum. I chose not to go with themes on the 73-87 forum because I didn't think there were that many active members to create themes from.
I also let people nominate their own truck. At first I didn't think it was a good idea, but so far it's worked out fine. It allows new members to get recognition.
I have to list the previous winners to prevent them from being nominated again. This gives more people a chance at the glory....
I say go for it. So far everyone on the 73-87 forum has liked the feature. It creates another reason to stop in often....