1) Laser, if perfectly focused, have very little attenuation in air. And you cannot correct imperfect focus by adjusting power. Not to mention distance has to be pretty large so good UV laser would start to lose its focus. So what's the point? I feel I'm missing something or misunderstood your idea...

2) You can try cheap manual syphon pump (on ebay you can get one for less than $2), with it you could remove salt water under resin. I did not try this myself because I do not have Peachy Printer yet, but I think this is easiest method to remove salt water. Of course, if somebody has better idea, they are welcome to share it...