Definitely if you can spend a night at 5k will help.

Wilderness athlete makes an altitude pack I've used inthe past, and its hard to believe it's helped, but altitude kicks my butt, makes me sick, was very worried for a elk hunt at 9-11k but I did rather fine. Went to wyoming last year, and felt almost no symptoms that first night at 7k, and coming from 190ft or whatever...

I haven't researched prescription meds too well, but I would recommend the altitude pack from wilderness athlete.
http://www.wildernessathlete.com/products.html
it's the hy-altitude

best of luck!

oh and def take it slow that first day! you're revved up and wanna work hard and get it done, but putting yourself in the sick bed the next day is not good, 2 avg days in the field are better than 1 kick butt followed by 1 resting all day in bed.

drink plenty of water, fruits/veges are your friends. being in shape never hurts, endurance!!

I'd bring a bottle of ibuprophen too, I've began using that the day I'll get there for the headaches, seems to help...