I went on a 750 mile road trip recently with my 536, which is the mobile version of the 436. It performed quite well on P25 systems with multiple sites (Indiana, Illinois, Wisconsin and Minnesota). I was using a GPS device, so that turned on/off sites as I got in their coverage area.
You have your choice of three ways to accomplish what you want to do, all of which involve creating a Favorites List for the system.
One is to use Location Control. This will "turn off" sites that are not in range. This is probably your better option.
Second is to Avoid sites that are out of range. You do not need to turn on Location Control for this.
Third is to set Site Quick Keys. Use one Site Quick Key for those sites that are within range of you. Use a different Site Quick Key for all other sites and turn that quick key off while in your home area. If you travel, you can turn that "away" quick key on, and scan the "away" sites.
You are on target for wanting to "lock out" distant sites. As I write this, I'm scanning the Indiana system - here in Louisville I can get a couple of sites. However, by the time it cycles through all of the sites, a fair amount of scanning time is consumed attempting to receive sites too far away.