Unframed paintings are often attached to something called a travel frame. Usually the painting is attached either directly from behind or with mending plates or on the high end with a kind of hardware called OZ clips. That way the paintings surface doesn't really need to touch anything. Given that you have already built your crate that may not be an option at this point. If the painting is dry you could wrap it in poly and put a layer of foamcore over the surface to distribute contact evenly across the surface and limit direct pressure from the cushions you have made. By the way from what I can discern from the photographs you have done a good job with your crate construction and especially your cushioning. People have a tendency to use too much foam - actually lessening the cushioning effect of the foam. As well the choice of 3" of foam is a very sound choice based on the best studies of such things (check out "Art in Transit" found elsewhere on the site). If you would like to discuss details directly with PACCIN folks don't hesitate to contact any of us by way of the contact information found on the "who we are" page. Current board members and virtually all of the folk in the emeritus section would be happy to help (that is what we are all about). As well if you would like to contact me directly you can do so at t.ashleymcgrew@gmail.com. Thanks for connecting with your "peeps". Almost all of us in the business are artists ourselves. Here's hoping your shipment is very successful on all levels. Ashley