You should already know what i think. Support xbower? Get my horse crossbowman build, it sucks in closed cities etc, but on open fields i can ride away from enemy even on palfrey. Just posting build again:
Mhm. Sure. HA. I prefer HC [Horse Crossbowman], because i am more accurate while riding a horse with full speed (5 HA skill) but i have not same great accuracy as bows, because width of reticule isnt that small, however i cannot get better reticule (above 160 wpf it doesnt increase accuracy in any way, maybe only shot speed, but not sure).
Build:
Level 30 (4 420 577 xp)
Strength: 7
Agility: 30
Hit points: 42
Converted: 4
Ironflesh: 0
Power Strike: 2
Shield: 0
Athletics: 0
Riding: 10
Horse Archery: 5
Power Draw: 0
Power Throw: 0
Weapon Master: 10
One Handed: 1
Two Handed: 1
Polearm: 137
Archery: 1
Crossbow: 160
Throwing: 1
Even some PS. And a lot of wpf in polearms/1h (only these two because 2handers require a lot of str and you only have 7).
Or in my build you can sacrifice 2 points in riding or 1 point in riding 1 point in WM for 1 additional str point, which is very important, if weapon you want to use from horseback/ground require 8 str, not 7.
I use lance/shortened spear/war spear (depending on what i like current day) with 0 ps (will be 2 on lvl 30) and 80 wpf atm. Guess what: it works to kill enemy horse archers, and with rest i can easly deal - just ride away with your 9 riding skill on palfrey/courser. On palfrey i can easly be faster than regular courser users with 5-6 riding skill. On courser... i am damn fast.
And of course, just to remind: using light crossbow.
HOWEVER
your build is good if you want to be on foot. And light xbow is nice, fast reload, and with 24 agi/5ps/8athletics you will be swinging fast enough with weapons such as Long Hafted Blade.