I tried finding a translucent 5 gallon bucket a few years ago for my Dust Deputy configuration. The only ones I could find were ‘food safe’ and because they are health related the cost was prohibitive.
I made a sign to check the bucket. Not as impressive as Julien’s solution but it works. To encourage checking the bucket use Gamma Seal Lids. They make the process less intimidating.
I have an Onieda 4" Super Dust Deputy with a fiber barrel. I have the same problem that there is no way to tell if the separator bucket is full. For me when I start to see dust in my clear dust collection bag I know the Onieda bucket is full and pulling saw dust into the dust collector. Some people cut out a window and glue in a clear viewing window but the clear window usually gets so dusty you cant see in.
I think the best thing to do is just to empty it every week or so and dont worry about if it is full or not just empty it.
See I was going to suggest just going to a 30 gallon bucket, and then you have to check it very very infrequently. My dust collection is poorly placed for servicing, but great for taking up unused real estate under my staircase.
Looks like a lot of people also have big containers, y’all must be making a lot of chips!