Okay, this may be my ultimate hybrid archer build. It gives you riding, ground archer, and melee skills. Basically the minimum in all 3, so you will have to compensate in each area with skill. You won't be a master in anything, but you shouldn't find yourself gimped because of the map or dehorsing.
It's a lvl 31 build. Uses Strong Bow. I prefer a long 1 hander because of slot restrictions, and 1 wpf in polearm is not undoable if you find the need to lance on some open maps.
Recommended path is to first get to 15 strength so that you can wield your primary weapons, getting PD and PS up first so you are at least effective when you do hit. Put all WPF into Archery until at least 140, though really should try to wait until 150 before putting into melee.
EDIT: Building this way, the build became viable as a HA at level 19. From there it just gets better every level
Level 31
Strength: 15
Agility: 21
Hit points: 50
Skills to attributes: 0
Ironflesh: 0
Power Strike: 5
Shield: 0
Athletics: 4
Riding: 7
Horse Archery: 3
Power Draw: 5
Power Throw: 0
Weapon Master: 7
One Handed: 55
Two Handed: 1
Polearm: 1
Archery: 150
Crossbow: 1
Throwing: 1