I'm just becoming aware that this is a hot button issue with some so it's probably not a great issue for a forum.
Still, I'll just say that I think it's a self-applied label. If a person wants to call oneself a fulltimer using whatever qualification they want to use it's okay.
If there was some kind of perk gained by using the term then it might be that some kind of consensus would be necessary but since there is no government assistance for fulltimers or special lane on the freeway reserved for fulltimers or some kind of Walmart discount for fulltimers then it really doesn't matter does it.
We think of ourselves as "traveling fulltimers." I've seen some who are stationary fulltimers - living in a RV fulltime but not ever moving it. And, of course, there are all kinds of variations in between.
I guess it's similar to calling oneself a "football fan" - within those ranks are those who love any game played with the pointy ball to those who are big fans of their 7 year old's peewee league. There's a big difference between the two but both can legitimately lay claim to being a "football fan."