Sometimes the easiest and best solution is staring you right in the face.
I put the flier in the diorama and realized that most of the I am trying to hide is not visible anyway.No sense in wasting a lot of time on something that will never be seen. Instead I will concentrate on what is visible and add a bit more to it, like fittings, piping etc...The tarps, if I show them at all, will have been completely removed or blown off over time.Once the whole thing is weathered it should be even more interesting this way,or at least more fun for me as I love the weathering process.
Speaking about finishing only what is visible,this practice has been well established with shadowbox dioramas, where a lot of what you don't see has never been completed in the round, especially detailed figures etc..