Normally where people get burned is that their boards get put in a "condensing" environment even though everything is specified as "non-condensing". But that's not a design problem so much as a specifications issue. tl;dr Don't sweat it and just do your design.

Understanding the Context

Good luck. Sweat Soldering is the optimum way to bond the board and the metal clad. Just solder paste is required. Going with adhesive will increase the cost of fabrication and also the cure temperature requirement for the adhesive will make the fabrication more complex.

Key Insights

Thank you all. So, the clock offset won't meaningfully affect your receiver. So, I wouldn't sweat it; if you can get a 26.041 MHz oscillator, that's going to be more than good enough. However, there's also an easy way out here that only needs a much easier to get multiple: generate 40.0 kHz, 60.0 kHz, and a (77.5 - 40.0) kHz = 37.5 kHz But if these are just test points (which I agree I think they are) and you don't know where they lead to, then you couldn't get any use out of them anyway... so I wouldn't sweat it.

Final Thoughts

Please specify the application more -- you give 1mV as a ballpark ripple figure, but not overshoot, and the voltage and current is unstated. For example, 1mV ripple on a 10mV supply would be pretty easy to achieve, but 1mV out of 1kV would make most analog designers sweat. The maximum rate of change or frequency also must be specified, because a mere length of wire has inductance which ...