Creating a 2nd sniper button- sounds simple, but it ain't

Hey guys, done my research and asked support over the phone but can't find a solution.

I'd like to create an additional sniper button for my Corsair Harpoon.

Well aware that there's a DPI toggle feature in the 'remap mouse button' section. I'm looking to hold down the forward button and change the DPI- but only when it's pressed down. Already using the backward button as a sniper key.

Maybe it's possible to create a macro that changes profiles? I'm thinking that the 'while pressed' feature in the macro's 'advanced settings' would do the job. The 'profile switching' feature itself doesn't help here, since that's a toggle- not a while held feature.

I'm grateful for any help. It sounds like a simple question but is more nuanced.

Cheers.