Please, stop, for your own sanity. You are not even sort of listening to what people say to you, possibly because you don't want to hear it.
For example, the $125/week overhead is flat wrong. It is more like $430 when you include both the RCI exchange fee ($239) and DVC nuisance fee ($190) per week. The times of year you want to go will coast you 105K Wyndham points per exchange, or 315K. (The 77K weeks tend to be in September when the heat and humidity in Orlando approximates Hades.) If you had a "good" MF at $6/K, your total is nearly $3200, so about double what you have in mind.
Even if you were 100% correct on your cost comparisons (you are not) there's still the matter that what you are trying to do (three weeks, back-to-back-to-back) is going to be insanely difficult via RCI. If your time has any value at all the amount of time you are going to spend trying to make this happen is going to eat up a chunk of that savings pretty quickly. Finally, trying to do this even if you are successful is going to be stressful, and that alone is worth something.
I'm a hardcore exchanger, and get one week in a DVC resort using Wyndham points (at a very good $/K ratio) most years. Even I would not try what you are considering, and I know my way around this because I've been doing it a long time. I get that you are trying to talk yourself into this, but I don't think you will find a single long-term TUGger who will tell you this is a good idea.
Yes, it's going to cost you real money to do this. But, DVC commands premium pricing and the people who own it generally find it a good value. If that's what you want to do, and you have the means to do it, that's what money is for: spending. Spend it.