My 147x is in storage so I can't tell you the exact measurements on mine. According to the Palomino website, both the 147x and 163x are 68" and 69" respectively and I would say it is fairly accurate; maybe a little generous depending on how they measure.
IMO anyone over much over 5' (and growing) is probably not going to be able to stretch out on either one, nor be very comfortable.
2016 Ram 1500 5.7 Hemi
2019 Coleman Light LX 2405BH
2015 Chevy Traverse
2011 Chevy Traverse (traded 2018)
2014 Solaire 147X (traded 2019)