I used to use saran wrap, just the regular stuff not carpet wrap. Works fine but can be time consuming. So instead I went to a fabric store, picked up some stretchy cheap fabric, a couple pieces at 10'x2.5', cost about $8. I wrap it around the tower and racks and secure it with hockey shin straps.
Works fine and takes about 5 mins to put on. I had an canvas shop quote me on building a tower cover it was something like $500-$600 and they didn't really think it would hold up in the wind.
My $15 solution has lasted two seasons and hundreds of miles, if it completely blows off I'll just get new material. It is getting worn it won't last forever but it's cheap and way better then scrubbing bugs.
This is a terrible pic a friend took while following me one day but it's all I have.