Welcome to another world of using and enjoying your RV. To start out, become familiar with the rules and regulations in the area you are interested in exploring. As mentioned earlier, a trip to the local authority office or visitor center is a great advice and should be done. These locations are often able to either sell or give you maps of that specific area.
The next thing you need to do, is build your confidence in boondocking, in that you will start learning what is a good location for you and what is not. No one knows your capabilities, confidence and ability of your RV and to get in and out of locations. This is something you need to take at a slow and deliberate pace.
My best advice at this stage of your Boondocking Lifestyle is to find some country roads, easy forest roads and travel them and look for wide spots or pull outs that your RV will fit into. Many of these locations are available with junctions of roads, rural mailbox locations and empty pen locations of cattle loading locations. Don't try for the really remote and cliff side locations at first, build up to that.
One question for you. Why would you need to find a dump location around 4 days? One of the issues of the Wild West, is that Dump locations are fairly far apart. Conservation on many things, water, dumping, fuel and food supplies will allow you to stay longer boondocking and away from citys or populated areas. You might want to start working on your skill in these areas too, to become more successful and thus, enjoy your boondocking experience.
Always, have fun!