Agreed. Wind can blow the rain in. I use an 8X10 tarp and hook put the 8' part, fore to aft and the 10' part side to side. You can set the boom height to take up most of the slack and bungee the corners to the cross beam ends. I did this ALOT on my H21SE and even camped on the boat with it on a mooring out at Catalina Island in Avalon Harbor. I did put a tarp under the sleeping bags since once in a while a wave would hit from underneath the tramp. I liked the Hollofill type synthetic filled sleeping bags since they still keep you warm if the bag gets a little wet from rain or splashes. If it's cool out, you will feel a breeze under the tramp if you don't use a tarp under you. I've used my spinnaker in a pinch under us to keep warm. Long story short, I had to beach my N20 in the middle of the night on an over night race and we used the mainsail over the boom and wrapped up in the spinnaker and our drysuits to keep warm. Thank God I had a cute female crew with me
It's a lot of fun to camp this way. Power bars and apples make great compact meals. Never pack bananas...unless you like baby food.