Another thing that I am not seeing suggested to you, is the handling time that eBay is so diligent and harping on. You are making clothing and if you are taking orders, how much time does it take you to create them?
Clothing is not like monogramming a specific name on a piece of jewelry, or a product that is all ready together. This is something to also consider. I am not saying that you can't do it, you are just making it harder on yourself.
Expectations of these Buyers are they want it yesterday. If you want to make some of your items up, and list individually instead of variations, then you are selling that specific piece. You would then list the item with specific details regarding that piece. It is possible to have communication with a buyer privately AFTER the transaction has ended.
eBay has 2 reasons that Buyers may complain about - item not received & item not as described. When doing special orders, if for some reason they don't like it, what will you do then?
Think about what has been said here, it's all very good advise. No one is telling you not to do it, but you yourself have found out first hand what kind of problems can happen and sometimes do.
" The real secret of happiness is not what you have or what you receive; it's what you share. " - anonymous