That should be relatively easy.
You can break it down and refine it later but, for starters, lets' say you divide your territory into 4 areas (1 a week).
Number them or give them more meaningful names like Kitchener, Barrie, Oshawa, etc., and make them custom ov2 categories and preface all with an underscore..
In those categories you put the names of the 25 'must see that month' customers alphabetically and preface them with an underscore. then add the other 125 'good to drop in' customers.
The underscored ones will come first In alphabetical order and then the rest.
If you now go
Drive to ...
Point of Interest
Poi near Home
--> more ...
the POI category: screen opens, starting with your 4 areas.
Within a POI category entries are sorted by distance from current location.
If you do not remember those 5 a day must see customers, make new POI categories, again for those 4 areas. Double underscore them as __11, __12, __13, __14, __15, __21, __22, etc. and put the names of the 5 customers of the day into them. They will still be sorted by distance from current location but since there are only 5 to look at you will know which one to choose for the day.