I'm getting my guy to put some costs together at the moment for a standard and high quality shirt.
Maximum print area is 21" x 17" or 53cmX43cm which is very large, but I wouldn't recommend anything under a medium shirt as it compromises the print size for those of a more magnificent size. ( our order for 2011....XLarge 35...Large 30...Small 1.... if you get my drift ) and female fit are not a problem.
As far as the back print is concerned with or without image the print cost for the back will be the same or you could even opt for 1 shirt with image, 1 without, the extra origination costs would increase by a maximum of approx £134, spread over 60 shirts for example increases the overall cost per shirt by just over £2 for the extra run.
I will put a few ideas together for a back image when I have a bit of time, but if anyone wants to throw a few ideas in, please do so.
Russ