bush, i think your plan is ambitious and sounds more like a two year plan to me. i don't think it can't be done, though.
in the end, it's your money and time to try it with. if you don't try you'll never know and all the "experienced" advice in the world isn't going to be able to predict the hundreds of variables that come into play.
ultimately, i think you're on an ok path. you have a goal and you have a working plan in place to get there.
it may take you a year or it may take you three and you'll most likely find your plan evolving as it goes.
as far as 15 hives vs. 2 or 3 goes my thoughts are that if they are all in one yard the difference in the time it takes to manage them is going to be getting enough equipment ready for next year more than anything. so your main challenges aside from the day to day management are actually somewhat distant.
start your 8 hives and evaluate things 30 days later and decide where to go from there. if it were me i'd try to go into the winter with 8 strong hives plus the nucs and see how it goes. if all that goes well you should be able to split in the spring and have the nucs to make up for any losses.
every journey begins with one step. good luck and keep us posted.