Can I use cards that is not a legal action? Let's say I am at the foot of the mountains and have basic movement card with only the resources to do water movement. Can I use the cards, not actually doing any movement but using up the cards so I don't have them in hand for the time penalty when camping?
The question is a bit incorrect.
Yes, you can spend resources on water movement, get nothing from it, but you won't get the time penalty 'cause you've used the card legally. It is still a legal action while you pay for it - it's just unprofitable.
What is actually illegal - if you try to activate the card without paying for it's effect. As I remember from FAQ or one of the threads, if you activate a card that requires to pay for it's effect it doesn't matter how many times you activate it - you still have to pay at least once, even if you won't get anything profitable from it. In other words you cannot use the commander card if you have no food/boat or horse tokens.