RKV requires 4 ranks in Hide. Hide is not a class skill for Cleric or Crusader. If you're cross-classing Hide, then 20 of your skill points are spoken for right from the get-go. Casting spells while mounted requires a Concentration check, as does casting defensively, so you need to keep that maxed. In order to have enough skill points for that, you need to take Crusader at level one, and have an Int of at least 12 - as Jack mentioned, you can take 2nd level maneuvers with your first Crusader level if you can delay it til 5. With Martial Study you could do that, as well as be able to take the higher level Shadow Hand maneuvers right away when you enter RKV.
Dragonscale Husk is still not worth it, especially since you have Protection From Energy that you can prep every day from Luck domain. I'm not sure which domain you chose as your Spontaneous one, but if you picked Luck then you don't even have to prep it. If you picked Pride then there's no reason not to prep it.
Remember that Planar Ally has an XP cost, and summons are usually a full-round action and have durations < 2 minutes. It's better to get an innate mount, if you can.
Which domain are you choosing for your Spontaneous one, and which power are you giving up for Divine Restoration?