Is the picture behind kind of stupid? Looks like a lifted HD pickup, and the 5th is using a towing dolly to turn it into a bumper pull? Did this guy not use the app?
I'm a TT guy, so maybe 5ers are different, but I wouldn't trust a calculator that didn't take into account the GAWR's. You can be within the other limits (GVWR/GCWR), but still be overloading your rear axle. Also, where you put the "gear/cargo/misc" is important; is it in the TV or 5th? Makes a big difference in where it is being placed as to axle loads.
Nothing beats 20 min at the CAT scales getting it all figured out.
2011 Jayco X19H (purchased 2015)
2008 Jayco 1007 PUP (purchased new, traded for the X19)
2012 Chev Traverse LT with TP