I do a lot of sailing on my Superlight with a 6.3 here on our inland lake. Good way to keep in shape for the windy days. And longboard freestyle is a fun way to challenge yourself a bit in light air.
Go into a tack, but don't move your feet. Bring the board all the way around while you stay on the lee side of the sail. Sail a ways that way, then push (with your back hand) the clew into and through the wind, following it so you are on the windward side of the board sailing clew first. Then release that back hand and let the sail swing around to the normal position. This gets more challenging in stronger wind, plus you can do it on short boards too.
Sail 360 in some breeze is fun... basically you just push the sail 360 degrees and end up where you started. The more wind you have the trickier it gets
If the RRD has a centerboard/daggerboard, have your tried railriding? Sailing across the wind, push on the lee rail with your back foot, then put your front foot under the windward rail and put the ball of your foot on the dggerboard. (you may want some protection on your shins / ankles the first few times). Once you can sail from that position, put your back foot on the rail of the board, then your front foot. Once you get the basic railride down you can do then stern first, clew first, with your back to the sail, etc.
Drew