First, I really wouldn't take acetone anywhere near Lexan. Almost all of my experience of plastic oil equipment was with acrylics (Perspex) and putting acetone on those would ruin them in an instant. Even the vapour from an open vessel nearby would cause crazing in the plastic as a reult of chemical action combined with the surface stress which exists in most plastics. Lexan (polycarbonate) might be more resistant. But I'd definitely try it on a scrap piece first, and wait a day or two to see if any delayed effects appear.
You may struggle to seal co-ax. Depending on its construction you can get leakage along the join between the inner conductor and its insulator, although if this join is tight it can take weeks/months for the oil to appear at the far end of the cable. More of a problem in the short term can be leakage along the co-ax screen, inside the outer sheathing. Running the cables out vertically upwards helps. But capillary rise can still beat you (this is the voice of experience speaking
).
If we needed an absolutely oil-tight co-ax feedthrough we usually gave up trying to seal the cable and put a panel mount socket in the vessel wall instead. Even then we had to take care that the socket we chose didn't weep.
Cheers,
GJ