Catalog weights have always been rather "fluid" over the years. The 1975 catalog weight for that boat is 59 lbs. There were also some trim out changes over time that changed actual weights. Seats went from solid ABS (white) to foam filled polyethylene (tan) for more flotation, decks eventually also changed from ABS (white) to polyethylene (black) and the vinyl gunwales on some models got a strip of aluminum angle added inside them to give them more strength. Other models eventually got wood-framed seats with webbing. Back when he was the national sales manager, Wendell Tremblay told me that the molds for the foam filled seats cost something like $10K each (in 1970s money) and so there were very few sizes made. On boats where the stock seats wouldn't fit in the desired places, wood-framed seats were used instead.
We occasionally used to take that 14'10" Mini Tripper, take the seats out, add a foam saddle and knee straps in the middle, pull the gunwales inward a bit with shorter thwarts and turn it into a solo whitewater boat. This was before the days when companies started offering similar boats tricked out especially as solo whitewater play boats.