It is not possible to "feel" the gear position of an amphib. At most there would be a couple of knot cruise speed difference, but hardly detectable. No matter what the actuating system, it is possible by visual inspection of the floats to positively confirm the position of each landing gear. It must become a pilot discipline that for every landing, prior to landing, the landing gear position not only be confirmed, but confirmed as being correct for the surface to landed on: "Wheels are up for landing on water" or "Wheels are down for landing on land". This spoken aloud in the cockpit, combined with a visual inspection of gear position is the only way to prevent this type of accident. I agree that in a Beaver, the left seat pilot inspecting the right float for gear position is difficult, but I have done it. The discipline is particularly important when distractions could be a factor in the approach phase of the flight, a new ATC clearance or traffic distraction are examples. A few amphibians do have gear "advisory" systems. When working, they will tell you the gear position, but you still have to confirm that the position is correct for where you're landing. Depending upon how they are wired, a popped breaker might have disabled the system. In a Beaver amphib, zero audible warning would be normal, so hearing nothing would not be unusual. For this reason, I dislike the advisory systems, preferring absolute discipline about speaking and checking gear position instead.
Considering the severity of outcome of an error, it's worth the effort to visually inspect, while speaking the required gear position. Let alone the cost of the damaged aircraft, emergency underwater egress becomes necessary too, as well as staying afloat until rescue, so there are lots of reasons to get this right!