Would a regular round analog gauge suffice?
First let me preference this with the following, I prefer all my work to simulate realistic instruments and equipment that are actually used on the aircraft.
I have search for awhile now to find a picture or documentation showing this instrument panel. I have a good reference for the panel that controls the deployment of the snorkel and sea snorkel (skimmer) and for selecting the dispersement platform. But nowhere can I find any gauge or idiot lights, nothing that deals with the level in the tank. There is an analog style gauge in the rear facing engineer station but I can't tell if it is tank fluid level or something else. In that same station there is a panel that looks like it might be an abbreviated version of the front panel that controls deployment and dispersal, it has some of the same looking colored light indicators.
Being logical about it, if I was designing this I would have the fill controlled by computer that could be set for a specific weight or amount with an indicator light when the predetermined level was reached. The computer would control the close valve. That is somewhat similar to what the dispersal logic and equipment currently does. As far as indicators for the hose or skimmer depth in the water. I can see convenience as a reason to have such indicators but I can also envision that being a function of piloting skills using the standard aviation altimeter equipment.
To answer your question though, yes, I don't think we could go wrong with that type of gauge, but I can't verify that there is any such gauge or even an indicator light.
You're aware that a good 60% of the forests around the Napa valley and Santa Rosa area, including a lot of the townships, small towns and part of Santa Rosa itself is on fire right now?
Yes, I am a native of Southern and Central CA with family in the south that live in high threat areas. I constantly watch the fire hazard in that part of the country. I too have been putting the AirCrane through its paces putting out fires in the chaparral country in the south. We had a really close call to our property in the last couple years. The fire burned maybe 10% of our land one year, but no structures. Could have been a disaster.