I have a '74 Argosy. The opening mechanism is probably the same.
Once you get the knack of it, they open easier. It's not so much strength, it's know how to use the side rods.
Granted the larger windows are more of a challenge.
I would suggest practicing with a smaller window to see if you can get it to open easier with practice.
Knowledge: "A gift to be shared. A treasure to receive."