Usually they are on the backside of the water heater. Should be a panel or door, open it or remove it to get to your water heater and it should be right there.
If you have a mattress/bed area over top of the water heater area that would be underneath, lift up the mattress, you should find about a 12"x12" cut out in the plywood frame of the bed to remove and "voila" it's there.
Find where the hot water tank is out side. go inside the rv there should be a access panel rite where your hot water tank is. sometimes they screw it down
I'm not familiar with your trailer but looking at pics online it appears that it is on the far back corner drivers side. Now inside, there appears to be panel to the right of your sink, beneath the counter, and above your furnace?! Should be a couple of screws on that panel. Remove them and it should be the backside of your water heater.
Edit: I see there are different floor plans within the 25rks family so the description above may not be accurate. Check behind the drawers and if nothing then find an access panel inside the trailer where the water heater is.
I have a 2010 25RKS. They are on the back side of the water heater tank under the kitchen counter. Easiest way to reach them is by pulling out the drawers so they don't block the way then reach in through the cabinet door under the sink. It helps if you're a bit of a contortionist .