Looking for a little advice. I have a vanity that has a "drawer" under the sink (see attached pic) so I'm unable to install a proper P-trap. That leaves me with the dreaded S-trap. But after searching this and other forums, I haven't been able to find an adequate answer to my issue. It looks like most S-trap issues are unvented, or otherwise attach to vertical drains. In my case, I have a vent only 4 inches away from the end of the "S". I just don't see a siphon happening. At the same time, I could envision possible gurgling. So here's the question, is this a rare instance where a S-trap is acceptable?
As I see it, I have 4 options.
a) Install the S-pipe as shown in the diagram.
b) Raise the T joint about 5 inches and install a proper P-trap
c) Cut the vanity and install a proper P-trap.
d) Increase the horizontal distance between the trap and the other half of the "S" thereby converting it to a legitimate P-Trap. I've heard that I need at least 2 times the pipe width. If I have 1.5 inch ABS, would that mean a horizontal run of 3 inches? I think this would fit.
My instinct tells me that the best ways to deal with this (in order) are b, c, and d. I'm hoping that no one finds an issue with a) but it's probably unlikely.
Really appreciate any commentary.