Spending my days in the Lisaland Test Kitchen. I think I have figured out our plan for sun-drying tomatoes. It is actually really quite simple....put them in the sun! For any of you who saw my first post about our sun-drying plan you know that I had the tomatoes under tight guard from bugs and kitties, surrounded by chicken wire and draped in landscaping fabric. Well, on drying day three in that set-up we woke up to some moldy tomatoes so it was back to the drawing board.
For round two or tomato drying I made two test trays, one that would be placed in the front windshield of Tom's car sitting in the sun, and the other to just sit out in the sun in open air. Each tray had a few different tomato varieties and some just cut in half and others with their seeds scooped out. After 2-3 days of drying, depending on the tomato, we were dry and mold free!
The tomatoes with their seeds scooped out really dried down to a bit of a plastic-y consistency, there was no real substance to the dried 'maters (these were mostly cherry varieties, I imagine with a larger variety you would receive good results with the seeds removed). I also didn't see much difference between the tomatoes dried in the car and those just out in the open. 
So, now that we know what we're doing we are brining out the big guns! We've got three big trays sunbathing outside as we speak!