That "Dam" Swim in Alabama

Hi all, Wanted to run my training plan by you guys and see if you think this is possible. Entering the 12 mile "Dam" Swim Sept. 23. River swim in Alabama. Water temp and conditions not an issue. It's USMS sanctioned. Been a swimmer since age 6 and am now 33. Swam USMS since 2002. Am considered a strong swimmer (placed in top 10 nationally as high up as multiple 2nd and 3rd place in all strokes and events.) Done some open water 5K swims and enjoyed them and placed in top 1 to 2 of women. This summer, focused on triathlons (sprint and olympic distance) and there was little focus on swimming. Have been training 2 to 2.5 hrs/ day 5 to 6 days a week among the three sports. I've got 2 months to train. Was thinking of swimming 6x/ week for 1.5 to 3 hrs per session at moderate pace (usually, I train at a very high intensity but my races are short - like 400 yds and less). I will be cutting out all the tri training to train for this race. Goal is to finish. If I DNF, I'll not be thrilled, but I'll be more disappointed if I don't even try the race. I'm someone who will wake up one day and say, "I've got to do this - whether it be compete and win a tri/ swim a 400 IM/ try a 12 mile swim, whatever. . ." And I always get up and at least try it. Do you feel this is a good plan and reasonable to try? Also, was planning on hydrating 6 to 8 oz of sports drink every 30 minutes during the 5.5 to 6 hr swim along w/ eathing some gu packets every hour or so. I've not done a swim this long. Should be very interesting to see if I can hack it. Just want to be safe though and stay hydrated and nourished. Will have own personal motorized escort. Thanks!! I've loved lurking here for the past several years.