Thanks gentlemen,
You would think that some aftermarket version of the Kent Moore tool would exist. I suppose we are too small of a market to attract product development. I was hoping there would be a filler tool similar to the old time oil buckets that had a trigger to start/stop oil flow.
In reality, it is not common to mess with the brake fluid reservoir once everything is dialed in, but it looks to be an aggravating process.
Maybe this is one of the reasons that original floor pans are so rusty as over the years they have gotten drenched by paint eating brake fluid.
The responses have given me some good innovation ideas though, thanks!