Setting: Low magic fantasy world, very close to clockpunk level of technology, but lacking ACTUAL clockpunk features
I have a tribe of people that live in a cold area of my world. I want them to have an exotic mount of some kind. I have always been fascinated by the idea of people riding reindeer, and so I decided this could be perfect with a little work. First, to be able to carry a lightly armed an armored knight, a reindeer would have to be much taller than they normally are, with a shoulder of at least 19-20 hands tall (about 7 feet?). I have read that their backs are not as strong as horses, requiring they be ridden foward to the shoulder area. This doesn't fit well, so I am going to have to change this. A powerful figure did a whole bunch of genetic screwing around on this continent; this gives me a little bit of license to experiment. How much stronger would a reindeer need to be to carry a 200 lb man with 60 pounds of armor and 30 pounds of gear? Is there something structurally unsound about their back, or are they just weak muscled? What is it about a horse's back that is stronger? If I use magic allow crossbreeding with a horse like a Clydesdale, what will change structurally, in theory.
The best Reindeer skeleton pics I have found:
I also want to give them a cool method of communication. I have read that Llamas will hum to each other as communication, in addtion to braying whent threatened. Is this unique to llama physiology, or could any of these animals do it with proper mental conditioning and instincts? Is this a major alteration or something minor I could just include?
Finally, if I don't call them reindeer (avoiding all of the santa-related references, as well as avoiding having to go into too much detail about these physiological changes), what should I make them? Do you have a cool name which is as simple as reindeer but different and still connotating deer?