I wouldn't use iodine for long term water treatment. As I read the guidelines, your trip is at the limit of the recommended maximum length of iodine use, but will be at a higher concentration than the maximum recommended.
Recommendations for short-term emergency use of iodine are generally limited to approximately 3 weeks, at concentrations less than 0.5mg/L for treating bacteria/viruses. (1,2,3) Wilderness water treatment would be close to 8-16 mg/L for giardia cysts, well beyond the recommended maximum intake amounts. (4,5)
For reference, 60% of school children in central China developed goiter where the water naturally contains iodine content of 462 [micro]g/L .(6)
1) Water and Sanitation for Health Project. Triocide Questions end Answers. Arlington, VA:U.S. Agency for International Development, 1980.
2) Zoeteman B. The Suitability of Iodine and Iodine Compounds as Disinfectants for Small Water Supplies. Tech Paper No 2. The Hague:World Health Organization International Reference Center for Community Water Supply, 1972.
3) National Academy of Science Safe Drinking Water Committee. The disinfection Of drinking water. In: Drinking Water and Health, Vol 2. Washington, DC:National Academy Press, 1980;5-139.
4) Backer H. Field water disinfection. In: Wilderness Medicine: Management of Wilderness and Environmental Emergencies (Auerbach P, ed). St. Louis, MO:Mosby, 1995;1061-1110.
5) Powers E. Inactivation of Giardia Cysts by Iodine with Special Reference to Globaline: A Review. Tech Rpt Natick/TR-91/022. Natick, MA:U.S. Army Natick Research, Development and Engineering Center, 1991.
6) Mu L, Derun L, Chengui Q, Peiying Z, Qidong Q, Chunde Z, Qingzhen J, Huaixing W, Eastman C, Boyages S, et al. Endemic goitre in central China caused by excessive iodine intake. Lancet i:257-258 (1987).