Highlight text without overriding character styles

I'm looking for a way to highlight text (for internal collaboration purposes) that I can easily "turn off" (for external sharing purposes). I've attached an example screenshot for context.

As of now, the yellow "highlighting" is achived via yellow boxes on their own layer. Visibility can then be toggled on and off with one click. It works, but is not ideal for documents requiring numerous highlight instances.

Normally, I would create an underline character style with a large weight. However, there are two issues I face with this tactic:

1) It overrides current applied character styles.

2) It doesn't work well across variant font sizes (as the underline weight can only be specified as a point size vs. say a percentage)

The files I work on require quick and frequent updates. For this reason, I'm looking for a solution in which the highlighting can easily be turned on and off. For example, creating the highlighting via multiple character styles could be problamatic to the job flow or leave more room open to error.

Fingers crossed that I'm missing something obvious here, so I'm throwing it out to the forum experts 🙂 Thanks in advance for your help!