I have now installed and calibrated my Mopeka Pro Check sensor on the fresh water tank on my 1995. The guidance from @Vigil and @Brubie made the job uneventful. Even though the 1995 apparently has a different tank arrangement from @Vigil's 2285, the same location worked out well. I installed it 12" from the curbside of the tank and 9" forward from the back of the tank. I did not find the 'lurking pipe' that @Vigil did but was able to feel what seemed to be some tubing running across the trailer between the water tank and the shroud about 4" towards the front of the trailer from the edge of the hole I cut for the 6" boat hatch. Everything worked out just as described in @Vigil's original post. I calibrated the sensor just as @Vigil describes. I won't be on a trip to road test it until we go to RITV in January but, in the driveway, I'm very impressed with the accuracy.
@Brubie got me thinking with his comment about the 6" boat hatch cover possibly vibrating loose during travel. Deciding it really didn't matter for this application, I removed the o-ring from the hatch cover and drilled a hole from the bottom side of the hatch through the threads and installed a #6 x 3/4" stainless steel screw into the threads to lock the cover in place. The screw does not protrude beyond the flange of the hatch. One only needs to remove the screw before unscrewing the cover. I filed out the hole drilled through the threads to make it easier to remove and reinstall the cover and added an indicator mark to make it easier to locate the screw hole when replacing the cover.
