I think this is what I'm going to do for the donation drive. Full scenes, each either taken or inspired from the game, rather than it happen in a void. Each marker is not what dictates the weight gain but the progression of everything, so there will be some small gains, bigger gains, but in the end she'll be quite large I'll promise you that.
Once everything is finished, Silver tier members will get a pdf file with every scene with a textless alt, and a bonus. That might be a concluding pic if the drive proves unpopular, or an extra scene or pinup if it does make goal minus any other attained bonuses past the goal.
Yup, we'll go above and beyond if the goal does, at least for a few "slots" as shown in the pic.