Here's the bags I use now:
Amazon.com: S C Johnson Wax Ziploc3pk Xxl Bigbag 65645 Bags Closet Storage: Kitchen & Dining
They make smaller ones, but these fit over the large size pedaltrain.
Here's a bad phone pic that I just took to give you and idea of what it looks like. I used to wrap it in plastic food wrap at every gig, but there were still seams where liquids could seep through when a beer is spilled on it. I actually owe thanks to another Fractal forum member for turning me on to the bags, I just can't remember who it was
This picture makes it look a bit more raggedy than it actually is, but this bag has been on it for over a month through 3 or 4 gigs.
View attachment 20392
I should also add that there is very, very little interference with using the pedals or MFC under the bag.