It will be crowded there is no way around that. However, we have done it and it is doable as you say with a good plan and willing participants with good attitudes. On the plus side the weather is usually beautiful this time of year in Florida.
I would work out a plan for each day of your trip for fast passes and back ups plans for those fast passes before you attempt to book these. This is a trip where, if possible, I would splurge and stay on site so you have access to fast passes at 60 days out. In addition, on site guest are the last to be turned away if parks reach capacity. Be ready to book as soon as your booking window opens up. If at all possible I would arrive the Friday evening before that Saturday because tons will arrive the Saturday or Sunday. That will give you a leg up on your booking window for fast passes by getting in the cue to book a day earlier for a 10 day window.
Also, research park hours way ahead and keep checking as Disney does sometimes change these at the last minute. Typically opening earlier. Plan adrs as soon as 180 day window opens up.
Know that the best strategy is to get to the parks at rope drop and take advantage of that first hour or two being one step ahead of the crowds. We typically did the first hour or so without fast passes and booked our first fast pass a hour after opening as close together as possible. That way we could add another for later in the day if available.
We also found that getting Magic Kingdom in first helped because as we got closer to Easter that park got the busiest. However, with the new Toy Story area and FOP in AK that may not be as big of a deal now. Regardless, we always did Epcot over the Saturday before Easter because it appeared to us to be the least busiest park that day. Also, for us we found more places to escape the crowds at this park. We found that the ability to duck in a show or have a table service meal (plan that adr in advance) helped it feel less crowded and stressful. We always checked out on this Saturday and headed home that night as we live in Florida and wanted to spend Easter with our family. So I have no advice for Easter Sunday day in the parks.
Ironically, the biggest obstacle we faced on our first spring break trip was our teens who didn't want to get up early to hit the parks at rope drop. This was frustrating since they were the reason we had to visit during their school breaks! Basically, before we book another school break trip again we set them down and explained that this was not getting booked unless they agreed to get up and out early without being a pain in the behind. The threat of no vacation at all did the trick for us. Really, that early morning routine helped us accomplish a great deal each day. We also made this work by doing our table service adrs for a late lunch and taking a break afterward then returning in the evenings. We also took one day off from the parks mid trip to rest up and enjoy the resort pool. This worked well as after a few days of park touring like this we all need a break to recharge and do it again. It also helped that our teens each requested certain fast passes and adrs. I intentionally booked those fast passes for the first ones of the day. I knew they were their must dos and knowing how long the lines would be if they had to do them without a fast pass motivated them to get up and out in the morning. Yes, it's manipulation but a Mom has to do what a Mom's has to do!
Good luck and enjoy your trip.