If you want to save weight (say around 8 oz), you can go with a pyraNet 1 under the trailstar. You can even have the length and width and zipper modified to fit your needs. It is basically 1/2 of the four sided pyraNet 2. Consequently with the pyraNet 1 you will have a very large vestibule under the trailstar, great for cooking and wet gear and about 3.5 feet of head room inside compared to the lower headroom in standard bivies.
Just another idea for you to think about.
After working with a lot of people who love the Trailstar, one thing about the its popularity is that it can be set up in many different ways to suit the camper's needs (praises to the MLD designers). That is why I think that it is one of the better designs out there. Consequently, one style of inner tent may work for one camper but not another. People have sent me numerous pictures of different set ups and have asked us to design an inner for that setup. One thing that I have learn about the Trailstar, just decide how you want to pitch the tent and then make or find an inner that suits your needs. There are many different stock designs from many excellent companies like MLD, GoLite, Six Moon Designs, etc. that may work for you too.
John at BearPaw Wilderness Designs
P.S.: Just to let everyone know: BearPaw Tents has changed to BearPaw Wilderness Designs. We made this name change because we do so much custom work with many different ultra lightweight products. We are no longer limited to tents. At the first of the year, you can still go to our original web site and you will be redirected to the new web site.