Here is the quick and dirty version I just whipped up, minus some of the peripheral items.
Mendevian Marine, male human fighter 6/champion 1, lawful good
str 15 (17) dex 18 con 14 int 12 wis 9 cha 10
traits armour expert, child of the crusade
feats feats exotic weapon proficiency (heavy repeating crossbow), rapid reload, weapon focus (heavy repeating crossbow), point blank shot, precise shot, weapon specialization (heavy repeating crossbow), rapid shot, crossbow mastery
mythic stuff champions strike (distant barrage), armour master, mythic rapid shot
gear (so far) masterwork full plate 1650 (550), +1 evil outsider bane repeating heavy crossbow 8700 (8233.33), belt of giant strength +2 4000, custom efficient quiver 1800, masterwork dagger 302, 1111.67 gp
I read the players' guide so I know that I would be missing out by having a campaign trait and mythic path that are at odds, but I really think it is the best fit for a crusader who made his own armour and weapons to suit his unusual combat style.
The reduced cost of the full plate and crossbow come from assuming he would have crafted the masterwork versions himself before the latter was enchanted. From a numerical standpoint the strength belt is not optimal but it is for pretending that the armour is "powered armour" . I would need a ruling for how many prepared clips (and possibly refill bolts) this version of the efficient quiver would hold. The normal efficient quivers is about 60 arrows/20 javelins/6 bows, but I was hoping to just have one that just held the crossbow itself and the clips/refills, since this is basically a stand in solution for an assault rifle.