Congratulations on your new-to-you TradeWind! I hope you get as much enjoyment from it as we have from our '64!
Our GlobeTrotter doesn't have any leg-type supports and is very stable. You may want to look into tightening the screws or replacing the 1/4" plywood platform with new if the screw holes are worn. Some other years had legs that dropped down or pulled out, but the way the '64s are it would interfere with the ability to open the cabinets or completely stow the bed.
If there aren't cabinets below (like on the side goucho - non-twin model) a leg could be retrofit and adjustments could be made pretty easily to accomodate a leg if you want.