The way I am used to forcing a route is by looking at the map and figuring my route first - at least in part. I then click on the map location where I want to or need to put a waypoint. In most cases this must be very specific - not just the town or general area but an exact place. I often use POIs such as gas stations as waypoints. They must be on the same side of the road as my line of travel. If no POI exists I can click the map at a spot on the side of the road (on the road but off to the side) I will be traveling. That creates an exact route using a series of waypoints which forces the computer and the map and the GPS to go the way I want to go and not the way the computer calculates a route. Even with Garmin - I zoom in as tight as the device will allow and use a stylus touch for my waypoint. This does not seem difficult or complicated to me and there may be other ways to do it but I find this to be the quickest and easiest.
Note - Guanajuato is in the state of Guanajuato - both city and state. Silao, Irapuato and Penjamo are also in Guanajuato. La Piedad de Cabadas and Yurecuaro are in Michoacan. Ocotlan and Ajijic are in Jalisco.
You can use the search function to get to an area (such as Portland or Brunswick) but to map accurately you must go to the exact spot in the town or wherever it is you want to go. At least that is how I choose to do it. As I try to point out in other posts above there are now new bypass roads - perifericos - libramientos - around some of the towns we may have on our route. We may not want to go through town. We may want to bypass. So it is necessary to put in a very specific waypoint to force the route to take the bypass route - if that is what we happen to want to do.
I know that in the US you can do a search using a specific address and there is a good chance whatever you are using will be able to find that specific location - though it may not calculate the correct route to get there. In Mexico it is rare that these programs or devices can locate a specific address - which is why we try to use Lat Lon whenever possible - much more accurate.
As I said before - and in response to a question above about why we want a computer if we have a Garmin - we have a 15 inch monitor screen built into the dash of our motorhome. I do realize not a lot of RVs have this sort of thing - almost none - very rare. But we have it so we use it. We used it exclusively with MS S&T for years but since S&T has not been updated for a few years we now use a Garmin along with our computer and S&T. Why do we want both? Because they have different things built in that can help us navigate and see things on the route - one might show some things and not others while the other might show what is missing.
You might say I'm into overkill. But we are all different and I like to know where I am going. I was a trucker running 48 states in the US for almost 10 years back before computers or GPS. All I had was a Rand McNally Road Atlas - I went to too many places to have local maps of everywhere I went. I usually called the client by pay phone (no cells yet) and had them tell me how to get to their location as I wrote down specific directions. I rarely got lost or made a wrong turn. Times change and we have lots of new technology and toys available to us so I like maps and figuring routes and I like having all the tools I can find to do this. I like to think it is fun.
What I am looking for is a replacement for S&T which may not exist now - or ever. I am hoping someone will see this thread and have some good answers. I think there could be other readers out there who might be interested in better ways to do things. I just wanted to open a discussion that might lead to some answers.