It is one of the bigger issues so good forethought.
Turns out it is a real problem. The best solution we found was to rent a condo in the area. That was great we had a vacation condo on the Gulf of Mexico, fantastic beach, all the luxuries......and then every morning we would get up and drive to the yard where we spent all day working like dogs! It was also expensive for the two months we had the condo but the days off really were great, loved that part.
OF course that is not really a good option due to expense. We have found a yard in Bellingham that lets us stay aboard. Thats a great idea and good security, the best really if you are just painting the bottom or something like that.
Otherwise staying on board and working on the boat is not good for us. Our boat is small and doing anything results in everything being upset and taking 10x longer, maybe more than 10x longer.
I'm still installing a heater, it has now been months. It would normally take me a weekend, maybe two. If the boat was in my back yard near my garage or shed it would be simple but living on the boat means you can't just rip things apart, particularly when someone else is using the boat for their work or study. Living aboard is also time consuming, particlualry when the marina has no showers, laundry, food or other services that save time. We even have to haul water and that takes more time than it sounds. Buying bits and pieces and tools locally is crazy expensive, easily adding 10% extra to the overall cost but the other option is even more delay.
So best plan is to own the boat for a few years before moving aboard (we couldn't afford that but still recommend it). Get all the big jobs done, all the jobs that need tools or lots of supplies. Spend enough time on the boat to figure out what those jobs are, like maybe a heater for when it is below freezing and fancy electronics for when fog rolls into the shipping lane you are in.
Then when you get the boat pulled once a year or so there is little work to do and you can handle staying on the boat for the night, or afford a motel and the car rental.
Have faith that the oceans are going to rise and flood the world, that plague and pestilence brought on by Climate Change is going to punish us for not believing. Please do as they say it is our only hope. :P