Originally Posted by A knack for horses
*And by trim I mean an even cut mane and tail, and managed ear hair
Please do not cut your horses mane even.
If it requires shortening please pull it. Cutting is a serious no-no.
In my neck of the woods the horses at a 4-h show are turned out like they would at a breed show. It is rare to find a kid who has skipped clipping and braiding/banding and you most certainly do not place in fitting and showmanship if you have skipped the details.
Obviously the horse is totally clean, clipped and show ready on that front.
For a stock horse breed go with what is the usual (yes, not everyone but almost everyone) does at a stock horse show.
A nice short mane that is banded if doing western (doing fitting and showmanship in western apparel) or braided in hunter braids if doing english. Some kids who do show breed shows do use fake tails but they are the exception not the rule. Tails are left out (not braided).
Clipping white legs is pretty common. Neat clipped bridle path. Ears, eyes, muzzle, fetlocks, hooves all clipped.