Your horse is beautiful!! What is the name of his color? I am kinda new and still trying to learn all the different types of colors lol Yeah the cleaning department is no fun! I think he tries his best to look like his half brother :P They do look shaped like each other! I honestly have yet to see a Rocky Mountain horse that looks like yours!
He is buckskin. They visually look a lot like palominos but with black points, manes, and tails. Also like Palos, there is quite a range of gold from pale to deep gold.
palomino horse - Google Search
buckskin horse - Google Search
And yes, mud somehow seems so much darker and dirtier on a light colored horse! LOL
Shape... yep no mistaking the near non-existent back. Make saddle fitting so much fun!
You know, now that you mention it I haven't seen another palo or buckskin Rocky either. Just the chocolates (beautiful!) or bays and chestnuts. And I can certainly say I have Never seen a striped one before!
Maybe this year you could do a skeleton, but in black and put his hair up in a mowhawk. Tell everyone it is a reverse x-ray, or that he stuck his hoof in a light socket.