It is absolutely possible to get a good snug fit there, and I speak from experience with my WBBB and winter Incubator. It took me a little while to figure out the propper adjustments to the suspension and end channels. Triangle Thingies can help with that but aren't necesary. Once I figured it out, it was a breeze from then on. I don't want to discourage you, as I consider the footbox to be far and away worth the occasional fussing to get that flat lay. I just want you to understand that there is a slight learning curve. The final product is well worth it!