Dodge did it in the early / mid 1960's with the Dodge Motor Home. Here's a vintage Dodge truck ad video. Check out the Dodge Motor Home at 5:36
https://www.youtube.com/watch?v=CmlWeWUD4IA
Travco took the reigns from Dodge a few years later. As part of the loan guarantees to the Chrysler Corporation during its financial crisis in the late 1970s, Chrysler was told to abandon the medium duty truck market (including the Dodge Motorhome Chassis) and concentrate on building light trucks

Me I did it because I'm tired of putting up and sleeping in a tent and hang in my butt over a log