My children are part Choctaw. I made regalia for my son when he was young. If you really want a rearing white horse, I might suggest that you just google or do an internet search for white horse rearing. There are many beautiful photos there,. You can either ask permisdion of the photographer to make a photo into across stitch design or use it if it is in the public domain. Then print out the photo you want and have it made into a cross stitch pattern, if you cross stitch.
There are several places on the internet that can make a design out of a photo. pictopat.com is one place and I believe the cross stitch stores online often have a place you can send to. Don't use ebay to do this,.as the quality varies! You can look at places online by again searching for photo to cross stitch pattern.
The white horse photos are truly spectacular. I am too old and crippled to ride now, but rode for many,.many years. A horse named Dynamite and another named Big Gray are partly why I have problems now! I hope you can find your heart's desire and make beautiful regalia!