I was a bit doubtful about sneak as well, but as you said I didn't know where to put my perks. I really didn't want to get a school of magic/enchanting/alchemy, and only having 5 skills really nerfs your leveling potential alot. I figured the hit-and-run playstyle while mounted would translate well into sneak indoors.

Thanks for the +1 anyway, I'm kind of hoping Bethesda adds some sort of Riding skill tree so that mounted combat isn't so overpowered. Maybe get a perk to actually be able to fight while mounted, then as you go further up increase the mounted combat damage, attack speed (say it's below foot combat for starters), as well as your horse speed and handling.