Try-on wedding dress different color than ordering

I’m picking between my top two wedding dress choices. The hard part is that designers only carry the sample of both in a nude/tan underneath with the upper layer having all of the detail (embroidery, appliqué, beading) in ivory. However, what I would order would be ivory on ivory.


I am nervous to pick between the two and saying the final “yes” without being able to try on the dress in full ivory. They can’t order a sample in that, and the boutique only had a very small ivory fabric swatch they slipped between layers for me to visualize what ivory/ivory would be.
Any suggestions of what to do for my Say Yes appointment to get a better idea of color to make the final choice? Would it be odd to bring an ivory bedsheet to my next appt to stick between the layers? Kidding but kind of not! Open to all ideas!