Taming R. montana means a few generations under cultivation; in the process easier to grow forms are necessarily selected. Your mix of Rhodophialas is a real .... mix. You mention true alpine species along with others demanding Cape bulb conditions and one almost subtropical. R. montana is not evergreen, all those you mention are roughly summer dormant. Planting them in the ground will be the fatal move. Instead, bury the pots in the ground so you have some room for manoeuvre in case something goes wrong.