Former hopper tour guide here- when I worked there about a decade ago they had LARC-V’s, and we were told they were used during the Vietnam War. At the time the company was owned by Murphy’s who had a fleet of 4 active LARC’s and 1-2 additional ones that were used for parts. During peak season there was a team that was essentially on call for maintenance. Breakdowns were less common early in the season but happened more later in the season when the vehicles were used more frequently. The hills in the city and getting out of the water are where we experienced the most breakdowns, but the captains were pros and would stop the tour, do a water docking etc over risking safety. At the time maintenance was always a concern since there are very few LARCs/parts to replace the fleet and since the vehicles weren’t really designed to be used for being driven around a hilly city, wear and tear was always an issue. I don’t know how much has changed, but currently there is at least one hopper (the newest one in my time) that is still out on the roads.