I have been giving this whole tarp thing some thought and tried to think how I would go about trying to protect my airplane from the elements.
The first thing to do would be to secure down the aircraft at at least 4 different points.Nose wheel,tail and wingtips ,as well as support those long fragile wings.
The wings could sit on saw horses with large tarp envelops covering them,same thing for the tail and nose assemblies.In this way they would be isolated from the damp ground and the grass would still get enough light to continue growing under them.It is only under the engine area that I could leave things a little muddy.Luckily the airplane is standing on sloping ,well drained terrain.