Just Wing it.
While the Milepost is informative about the main routes, it barely covers the roads off the beaten path, which we like to explore in our TC, verses boondocking just off a highway.
In addition to the provincial parks in BC (more than 330) and AB ( more than 80) there are provincial Recreation Areas with camping (usually free; a small number of sites 1-5). BC has over 1,200 of these dispersed campsites (a table and a view, sometimes not even a table) that they list as recreation sites. AB has more than 200. Plus there is random camping (aka boon docking) on Crown land. Add to that thousands of trail heads to overnight at and then taking a morning hike before traveling on and you have lots to see. Most of these recreation areas are located on gravel Forestry Roads, with ratings of RV, then auto, then 4wd to inform you of road condition.
Backroads Mapbooks makes detailed map books for these provinces showing the recreation sites. Plus they have a digital version for GPS. Or you can contact the province website and ask if they have Point of interest files (POI) that have the name and gps coordinates for each park or recreation site for download or e-mail delivery so you can put it into your mapping program.
The provincial websites also have lots of on-line tools and interactive maps for locating parks and recreation sites. But access will be limited once you start traveling. Might consider a pre-paid canadian cell phone to avoid outrageous data roaming charges in Canada by US companies.
Also keep in mind Glacier will still have lots of snow in May and only the low elevation portions of the park will be open.
Canadian Topo maps as PDFs can also be down loaded for free.
National Map of Canada - Toporama Choose layers to select information to display
CanTopo and Can Matrix Digital Maps of Canada Choose Themes to select map type (raster) and then select map type to load indices
Camping in ABAB province base maps 1 to 50,000 scale up to 1 to 2,000,000 scaleCamping and RVing in BCBC Recreation sites and trailsBC Provincial ParksiMap BCBC Topo maps 1 to 20,000 scale available for downloaded free as PDF file
BC Topo maps 1 : 250,000 scale not geocoded downloaded free as PDF file
US Forest Service Topo maps 1 to 24,000 scale (7.5 minute) downloaded free as PDF file
USGS TOPO maps Current maps 7.5 minute. Non-current digital version of raster maps 15 minute and 1 degree downloaded free as PDF file. Go to the layers icon and turn on indices to select topo maps
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