I think you can install windows 7 and customize the partition to be about 80gb, which is hopefully the smallest drive you’ll need to support. Do your customizations and sysprep it with an unattend option to resize the partition to fill the drive. Shutdown and take the image as single disk, multiple partition (it just works better).
When you deploy, depending on your sysprep options, it should fit onto any drive 80GB and over and auto expand the partition to fill the disk.
It’s more complex than this because of all the sysprep steps and making the unattend file, but I think this is the route you’ll want to take I think.
I do NOT use single partition resizable with Windows 7 because it may not work, and if it dies in the middle of resizing the partition, it makes it unusable.