Nor knowing all the 25 changes over the years, I can only offer the configuration of Journey On, a 2005 model.
The tank is under the v-berth. A line comes out of the lower port side bullkhead to the pump in the hot water compartment. I installed a filter and drain valve at the point where it comes out of the bulkhead. It doesn't come with either.
A second approach, which is what I used, is to trace where the pump inlet line goes. Drain the tank with the pump. Then, at the lowest point of the inlet line, install a filter and drain valve. that should work wherever your tank is.
Boris