There are 2 character sheets for AD&D 2E in Roll20's drop-down selections. The more advanced one, sometimes called the Red sheet or the Parchment sheet, (Not the AD&D 2E Simple Sheet), has accommodation for Dark Sun features. I've got a 2E enthusiast's play group on here. It is called the Roll2E Tavern and can be joined in the Roll20 LFG. We have a discussion group for things like this if you want to apply.