I met a Swedish guy on the Chunnel about 10 years back with a similar set-up on a much modified Electraglide. It was all about his Iron Butt credentials, which grew pretty tedious TBH.............yawn.
To top off the rear rack he had an enormous custom aux fuel tank, which acted as a backrest in place of the tourpack - reckoned on 4-500 mile range, bladder management allowing (sorry Paula but your image just flashed back), for his marathon rides. Not my idea of fun, but it takes all sorts I guess. Was the fella interested in what/why/where the rest of us were going? ........... not remotely, he preferred the sound of his own voice; perhaps it was the loneliness of all those hours alone in the saddle.