Alcohol may be out of your body in a day or so, but they can have tests now that detect alcohol metabolites or some crap that are in your system for up to 72 hours after having as little as one drink. Had a good friend who worked for the state-run alcohol education program they make all the drunk drivers take, and they can and do test for alcohol and if you've had a drink within 72 hours prior to the test it WILL show up.
I've been on felony probation before and I can tell you they test for pot, cocaine, amphetamines, PCP, opiates and benzodiazapines (usually, but not always) all one one little dipstick. You say it's a lab test, but I'm sure they do a preliminary dipstick test and unless they get a hit on that dipstick they don't typically send it off to the lab for analysis because it's fucking expensive.
Yes, LSD can be detected in your urine, but only for about 24 hours. Nobody tests for LSD, unless you're arrested running naked down the street and muttering under your breath like a crazy person and they can't figure out what the fuck is wrong with you. Drug tests for psilocybin mushrooms exist, but are also very uncommon. Not included in a standard drug test, at least.
You're definitely better off sticking with the occasional hit of acid or eight of shrooms than to fuck with some bullshit cough syrup. Cocaine only stays in your system for about 72 hours, as well, so if your tests aren't random you can definitely partake in some of that once in a while, too.
I think your best bet is to stay away from drugs while you're under the supervision of the court. Otherwise, you're going to screw yourself over and end up in jail when you could have had the charges dismissed and gone on with your life.
It's not fun being a convicted felon. Be glad you got busted for a drug charge and not some other bullshit charge that doesn't have the option of a deferred sentence.