It was quite likely done with this stuff, it is high heat resistant and will bond to the foam backed vinyl and to the fiberglass as well as to wood. It is the same product that I found when I took the foam backed vinyl off the fiberglass interior in my Sunrader. Also the same stuff that was holding up the carpet on the walls in my Campster
. It has been around for ages.
They do make a spray version. In a factory setting it most likely would have been purchased in bulk and sprayed on. It is the old go-to standard contact cement. I remember my folks using it when they made projects in the 1950s and 1960's. I still use it, great product and easy to find in local hardware stores.
While there are lots of newer adhesives around that are good I like this one for brush on and or roll on applications where I need a contact cement. I used some 3M 80 and 3M 90 recently and they also worked well but were pricey per square foot of coverage. Still the convenience of a rattle can spray is certainly nice at times. But if your budget is tight the Weldwood is easy enough to do with disposable rollers and roller pans. Work as a team if you can because that makes it much easier to install large pieces and pay attention to the directions for how long it needs to dry before putting the two pieces together.
Remember...practice makes perfect. practice with some scraps and the glue so you know how quick it grabs, etc. You can buy it in little pint size cans and even in small bottles to test it out before you invest in a gallon size.
It is the adhesive I will be using to put the foam backed vinyl and the marine vinyl that has a fabric type of backing on the surfaces of my Trails West Campster
project. It will also be what I use if I decide to put laminate on my countertops and table. As I said, it is budget friendly and easy to find at the local hardware stores. After getting only a few square feet of coverage out of a can of 3M 90 that I paid $20.00 for after tax my mind was quickly made up as to which adhesive was the clear choice for the job.