What is being towed so often in your scenario?
no net-positive use-case for the average consumer
I’m not talking about professionals, or people who take their boat out four times a week. That is a specific need for a specific tool, or vehicle. I’m talking about people who daily drive these things to the grocery store and work. So, the average consumer.
The vast majority of games work just fine with 16gb RAM. I recommend running your higher speed modules as dual-channel and selling/repurposing your previous hardware.
Unless they are the same brand and specification, patchwork RAM tends to have compatibility issues leading to software hanging and potential crashes. YMMV.
ETA: Honestly you’re more bottlenecked by your CPU. I’d recommend finding a used Zen2 chip if you can, such as the Ryzen 5 3600. I have a 3600x in my home desktop with a basic Coolermaster dry tower. I’ve never gone over 70°F/~21°C on fairly high settings of TW:3K. That should speak enough of Zen2’s performance.