What's the make and model of your vertical GPU mount? From the image you shared, and with that being the only bit of info provided, the standoffs there do make it seem like you can move the PCIe slot on the extension away from the motherboard. Though please keep in mind that moving it closer to the side panel that's not ventilated will hinder your GPU temps.
Then again, I'm curious to learn what your GPU and CPU coolers are.
^ We advise users to mention their specs in the thread's body as opposed to stating specs in my sig since sig space specs can and will change over time. When that happens, this thread and their suggestions will be moot to the end user in the same boat as you're in today/now.