Hello...I've been reading this website for a while and thought I'd join. There are a lot of really interesting replies to questions, and you folks seem to be very knowledgable. We are retired (US citizens) and have been RV'ing in Mexico for a couple of years now during the winter months. This next season we plan to take our truck/trailer to the Lo De Marcos area (45 miles north of Puerto Vallarta) and stay for 5 months. Then, instead of heading back to the US, we'd like to head up to the central highlands for several more months. Perhaps returning to the USA for several months (or maybe not). We're interested in advice from other RV'ers to find out if it's a big deal to stay longer than 180 days: i.e., obtaining FM3, vehicle permits, etc. I'm sure there must be other RV'ers who stay longer than 180...we've just never met any. Any advice would be appreciated.