I wouldn't recommend doing this unless you have good faith in your team, but without much magic resist your arrows should do around 1300 damage and your next attack should deal about 800 without armor when maxxed.

Nashor's tooth is the first permanent item to help with autoattacks and to prevent you from straying too far away from AD Ashe, and helpful for cooldowns. After that, get a void staff for magic penetration. Lich Bane is so after every arrow or volley, your next attack will deal a lot of damage as it combines your AD + AP into damage. After that comes 2 Rabadons to boost your AP, and you can switch out your boots for a third deathcap if you feel up to it.

Teleport is so you can follow up on your long distance arrows, and Fortify is because you have 2 extra mastery points after max AP and spell penetration so splash damage turrets help defend and the 4% defence is simply to tank better, as you are very squishy and you don't have any boots.