RTMM Missing Cabins (Refreshed 06.05.2020) covers those two.. (but I think you have the Missing cabins already setup as I recall but give it a check.). Now some of the cabins are very hard to find but after searching will eventually locate them.
Use/import the USFS Cabins.csv into your plan G (By Dieter). That csv files adds all of the USFS cabins from the Cabins Page). (LINK:
https://return.mistymoorings.com/mistys/#dieter)
Shows in the csv file (decimal-Lat/Long format):
East Creek Cabin 60.70555496 -149.7486267 1697 339.53 Chugach National Forest
Devils Pass Cabin 60.62138748 -149.7524872 2385 339.56 Chugach National Forest
So if you import that csv file into plan G, then close and restart plan G, load up that flight plan and follow the route on the map and it should show indicators on the plan G Map for those cabin locations.
Norm