We lived onboard a forty footer for almost twenty years and lived well. Our cars were not filled with junk, had no of boat storage and our boat looked empty because everything was stowed properly all the time. We were off the dock 2 - 4 days per week and it took less than 5 minutes to get underway.I would encourage you to read some of CruisingDad's posts. His family and he live aboard. Now, granted, it's a family of 4 with two boys, so things are very different from your current situation, but from what I've read most live-aboards tend to say that it is a real pain to take the boat out every so often. You basically have to live in a state of constant readiness, or resign yourself to having to spend a fair bit of time (hours? a day or two if you're like me?) stowing stuff before she'll be ready to sail.
Two people (who don't believe in camping) and four people for 3yrs. (my son and his wife) had no problem keeping "stuff" to a minimum). For twenty yrs my entire social circle was liveaboards, many of whom (on much smaller boats) were as organized as we were. Some on 50' motoryachts had so much junk there was no where to sit down. It all depends on your personal proclivities.I'm not sure it's fair to compare living on a 40' with living aboard a 27. I think it's much easier to keep things stowed on a 40.