well, you can do a solo quest on any fatalis and you've got a good bow to start with. one question: do have the final upgrade of the akantor bow called the Tyrant's Wrack? if not, i suggest that you upgrade the bow first. if you do, then try using bombs! once the fatalis (any kind) gets into armor mode, you need to use bombs instead and sink in some damage. if you have the alchemy book, then you can carry up to 22 large barrel bombs! 12 for the large barrel bomb+ then another 10 for the large ones using alchemy. i try to break the wings first since they're very valuable if you need to create any fatalis armor then aim for the head to get the evil eye.
breaking the chest is easy since you can always do random shots and hit it eventually. after every 25 minute encounter for 4 times at best, you can slay the monster. there's a spot where the white fatalis always lands after summoning a lightning attack. remember that spot where it lays its head and you can always place 2 bombs there. when the head is close enough then shoot the bombs.
i recommend using the volganos x gunner set and equip the load up skill from decorations to unlock the 3rd charge level for the akantor bow. bring lots of power coatings, 1 mega demon drug and/or 10 power seeds to boost up the power coating and steaks. no need for mega juice since the armor has a fast charge skill. also maintain at least 60% hp to activate the survival skill just in case!