Have you checked out the Dundjinni forums? You will find a veritable treasure trove of just the sort of things you are looking for. I know there are at least two different types of tents, but there are probably more that I haven't looked for. Use their search feature at the top and type in tents.
As for the coast line, you said you are using a fill? Have you tried changing the angle of the fill? If you are using a blend mode, you can try turning off the eye in the left column to find which blend mode is causing the effect. Also, you could try adjusting the scale of the fill.
Since I'm not entirely sure what you are doing to achieve the effect I can't give you any more guidance than that.