[JRTJH]

Tanks on both ends of a trailer is definitely not exclusive to toyhaulers with an extra half bath. The contents (black and gray) may be different, but my Cougar XLite has the galley tank in the back with the black and bathroom gray tanks in the front. There's "pipeage" to the center from both ends, very similar to your arrangement. I've no idea how long the Bowden cables are on my tanks, but I'd guess they are 3'+ on the front two and the back is a 18" solid rod. The two valves with Bowden cables are "not in line with the handles" and the one valve that is "in line with the handle" has a solid rod actuator.

There's nothing "exclusively different" in your tank arrangement (other than contents of the tank) and my Cougar. They all "work the same way, regardless of tank location and "distant tanks" are very common.