Looking at your build, if you take out the magic circles and the mana investment you get 390 LPs, enough to train to 90 STR and 90 DEX and have 50 LPs left (which you could use to get master blacksmithing-.. and if get rid of pickpocket, also master bowmaking). That means 152 STR and 128 DEX - considering you wouldn't make/ buy spirit potions, but STR/DEX ones, a hybrid looks doable, at least on paper.
Later edit: A bit of theorycrafting
- 113 LPs - 20 + 60 + 33 LPs to get to 71% xbows + 4 from dialogue choices + 15 from set = 90% xbows (I think i read you can get +5% from books and another +5% on the best xbow, so maybe even 100%);
- 27 LPs for all trophy skills (10 skins, 3 lizard skins, 3 claws, 3 teeth, 1 mandibles, 1 stings, 1 wings, 1 fat, 1 shells, 1 tongues, 1 shadowbeast horns, 1 hearts);
- 20 LPs to get 1H to 30%;
- 35 LPs for master blacksmith;
- 35 LPs for master bowmaker;
- 60 LPs for master alchemist;
- 125 LPs to get STR to 75 (20 + 60 + 45) + 60 from made/found potions = 135
- 125 LPs to get DEX to 75 (20 + 60 + 45) + 60 from made/found potions = 135
TOTAL = 540 LPs. It all comes down to how many extra bonuses you get.