The amount of space required for your group is hard to estimate. Sometimes the boat is never big enough for two let alone 4
children not yet grown with a lab. I think this is something you need to
work out together especially since the goal is 3 years out and the long term goal farther yet. It would help you a lot to try out a
charter trip just to give the
family a taste before you jump in with
purchasing a boat.
It's easy to see you are excited but it's hard to get everyone excited and still keep them excited over a long period of time. I think they all need a good taste of it to build a little excitement and commitment to liking the idea. That keeps them going until you finally are ready. 3 years to them is almost forever.
Dogs also seem to either take to it or they don't. I think most would rather go than be left behind and that is the way it is with our dog. Ours does fine but I don't think he really likes it as much as he likes to be with us. He snoozes in the
cockpit shedding dog hair just fine.
All this is to come back to the beginning. Working this all out with your crew is perhaps the hardest part and starting with some sailing sooner without the pressure of
living aboard may be a good idea. How you all work together in close quarters also makes the boat fit the crew better as well. It is as much effort to find the boat as it is to fit the crew.
Single handing with a large crew as yours needs to be adjusted by the types of trips you can take. Small children under 8 are a bit more overhead since they understand a lot but can't often do it very well under pressure. Helping your girls grow into this adventure is only going to help your ability to work the boat on the hook as well as on the
water.
No boat comes easy to single hand. It's more a matter of
learning how and practice is always the road to complete skill. The auto pilot is the dirty little secret that makes almost any boat able to be singlehanded. It can hold the
wheel / course for you as you tend to all the things you need to do. Controls handy and led to the
cockpit always help even when not single handing and it is common with many boats and not limited to certain brands.
The
money does matter. It limits your choices but it also has to balance the budget. The continued operation and
maintenance is an issue that easily dents the balance sheet so all those costs have to be figured in. I really think if you expect to take off in three years you'll need almost a year to get yourself and the crew ready with some sailing experience. That can also buy you time as you learn all the things you don't know you need to know.