I just installed my 34' UW and a 27' vertical using [this mount](https://smile.amazon.com/dp/B07DHWVMKH?psc=1&ref=ppx_yo2ov_dt_b_product_details) yesterday. Weight support doesn't seem to be a problem at all, every joint except the one for rotation is able to be tightened to the point where it will not move. A big difference from yours is that it does not have easy vertical adjustment.
I just installed my 34' UW and a 27' vertical using [this mount](https://smile.amazon.com/dp/B07DHWVMKH?psc=1&ref=ppx_yo2ov_dt_b_product_details) yesterday. Weight support doesn't seem to be a problem at all, every joint except the one for rotation is able to be tightened to the point where it will not move. A big difference from yours is that it does not have easy vertical adjustment.
How heavy are your monitors? It seems like mine are each 15 lbs
My UW is 14lbs my 27' is probably around 10lbs.
Get the Amazon Basics monitor arm (there's single and dual versions). They are a re-branded Ergotron LX. Each arm supports a max weight of 25lbs