I have never had an issue with the case. I probably have 50 days on the river with it so far. It has been down some long swims. It is a GSI Lexan Utility Box. I also do random dunk tests where I leave it in a bucket filled with water over night.
The switches I used were actually from the marine section of a store. The rubber boots for the switches were part of them. A switch getting wet on a fresh water river trip really wouldn't matter that much anyway.
The way I look at it is the trailer harness itself is not completely waterproof and considering how many people back their trailers into a lake with the lights on in order to spend at least ten minutes loading on a motor boat is way more time I would have the pump on while paddling the river on a bad day.
I do remember reading on the package that the efficiency of the pump was also based on how high the water was to be pumped up relative to the pump itself. This is referred to as head.
Here are the specs for the pump I used:
Attwood V-Series V1250 Bilge Pump
The picture is for a V750 but it looks exactly the same.
4731 ltrs / 1250g.p.h. open flow
Open flow beats the competition by nearly 1135ltrs / 300 g.p.h
Only draws 2.6 amps - 40% fewer than competition for longer pump and battery life
Compact at only 4.9" in height
Caulked wires prevens wicking and motor damage
Low power consumption, has base bracket allowing dual position mounting (either horizontal or vertical)
Flow rate per number of vertical feet (head) to pump up:
0.0 feet - 1250 GPH
3.3 feet - 950 GPH
6.7 feet - 500 GPH
The max head rating is 11 feet.