Diatonic cluster

Hello ! I have come into a problem I want to solve but I am too dumb to solve --

In my attachment I have a screenshot of a specific within my work I am writing, where I want to add a large cluster for left hand, bass clef (played by putting half of a hand, silently, in the selected range for resonance effects, tired to explain), but a diatonic one (all white keys within the range given in the image I attached) but I cannot figure out a solid, pain free way to notate it, that would look clean and not bulky.

I have seen few options with brackets and the specific symbols for clusters, but they work within a small range. Are there any solutions to this ?

I would gladly hear some,
Thank you in regards