Another source of maps in Mexico is the SCT gov't website where they post the latest gov't maps in .pdf format - these are the maps others use to create their maps. You can zoom in and move the maps around with a little practice. These are similar to full size road maps if on paper. They measure about 3'X3' if zoomed to 100% - you can zoom out or in to get closer and better detail. But they only show main roads - no city streets or small roads. Good for reference but not as much detail as S&T or Garmin. Here is the web address where you can download these .pdf maps for FREE.......
http://www.sct.gob.mx/informacion-general/planeacion/cartografia/mapa-por-estado/
S&T will still work for years to come and I think the guys on Laptop GPS World will have lots of ideas to think about. MS and everyone else now wants us all to do our mapping online - but we cannot always be in places where online maps are of any use. S&T and Garmin are our only hope. I much prefer S&T because it is so versatile. The biggest problem will be that we will not see when new roads are built. I already note that the NW section of Arco Norte is open and operational but not on S&T. I have not looked for it on my Garmin. As Mexico (and the US and Canada) build new roads they will not be on the last version of S&T. Though new roads are important I think there will still be many ways to use S&T in the future - at least for awhile.
I know of no maps or GPS for countries beyond Mexico going south. Maps may exist but I have no idea where to get maps or to use in any GPS.
The link I posted for UV and filters shows websites where parts can be found to build systems. Many say that the coconut charcoal filters are the best for taste and odor so that is what I use and pass on as a suggestion. The coconut filter is the only one I have found to provide fresh tasting water.
I built a little sort of stand I put on the ground near the tap water source and hook up water to that. There is a 10 micron filter for my first stage. There is an incoming water pressure gauge (not for MX so much but in other places we have seen up to 140lb of pressure that would blow our hoses). There is a pressure regulator. There is another gauge showing my regulated pressure. There is a valve I can open with water turned off where I can pour bleach directly into my water system beyond the first stage filter. This stand and the devices are connected by PVC pipe so I pour bleach in there so when I turn the water back on the bleach goes into my storage tank.
I speculate that the reason things like S&T and the Church book are not being done again is that people buy one edition and never buy another as things change and updates are added to new editions. So sales lag and it is no longer worthwhile to keep issuing new product that not many buy. We bought every edition of the Church book and every version of S&T through the years. But one buyer does not make a market. Maybe Bill Gates has all the money in the world but even MS does not put out products that the public does not appear to want. Online maps of the US have made S&T irrelevant to much of the buying public. Too bad. Online maps are of little use to those of us who seek new adventures.