Yes, with a 3600 lb. pin, you should definitely go dually. Which Thunderbolt are you looking at? I have a 2016 395amp, it has a 2800 lb. pin loaded for camping. I've been towing mine for the last 2 seasons with a '15 F350 srw. The light pin was a major selling feature for me on the XLR brand. We love our Thunderbolt, we spend many nights in it during the summer.
2016 FR XLR Thunderbolt 395AMP
2015 Ford F350 CC SB 4x4