Party Dress in Silk Chiffon

My sister is getting married at the end of September. I will be her matron of honor. The bride will be wearing a short, full-skirted 1950s style dress in vivid pink.
I have decided to also go for a full skirted silhouette and have more or less decided to use a Butterick pattern of a plus size princess dress. I would need a petticoat to fill out the skirt. I am also considering adding sleeves.
I purchased a length of silk chiffon in palest yellow, printed with a jaunty collection of roses and fruits. I was able to go to Hi-Fashion Fabrics on a rare trip to Sacramento. I had a good time shopping.
Over the next three months I would like to complete this party outfit. There are many things to do.

• Make petticoat.
• Make muslin of party dress.
• Perfect the fit.
• Begin the lining.
• Begin the chiffon.
• Complete construction.
• Hem, make belt, hairpiece.

I am seriously considering underlining the yellow chiffon with a white chiffon. This adds a significant expense but I have the suspicion that it will significantly "fill out" the floaty chiffon effect.
Under normal circumstances I would solve this dilemma by going shopping and looking at a variety of high end silk clothing. Living in Chico, I have little faith that there will be much to look at. Maybe I should go downtown and to the mall and just look around.