I use wide backing all the time. I do tend to prewash them- mainly because they often have large- deep set wrinkles in them due to being folded & wrapped on the bolt. I prewash as usual then put in dryer, taking it out when *Almost* dry. Then I drape it over my frame to finish drying. Laying it out before it’s completely dry usually keeps it fairly wrinkle free so I don’t have to iron it.
When you remove it from the washer give it a good shake, - fluff , so it doesn’t try to dry in a big ball. This method has worked for me for many years. I don’t think I’ve pieced a back in at least 12 years.