you can buy the standard test kit (and just look at it) in most drugstores. one of the ironic things is that the "safest" drug is also the one that persists in your system the longest. I'm not 100% it tests for LSD and I'm not at all sure how long a dose stays in your system to make it relevant. My suspicion is that everything in the 2-c class is used at such small dosages that anything looking for PEA compounds (via MDMx varieties) is going to be effective only very soon after use.
if it comes back positive it would not be for 2-cx, but for one of the listed substances, & then get sent off for detailed GC testing which will list everything, and it would definitely be against prob.
my bottom line: if you know you are going to have at least a couple of days lead time before getting called in, wait for the first one, then afterwards, do a small amount of 2c-e & run one or more drug tests on yourself at intervals to see if you ever get a positive.
otherwise i'd still say it isn't worth risking probation for it.
here's some info on the standard tests--don't even need the drugstore after all:
all tests:
http://www.craigmedical.com/drugtests.htm
standard 5-panel test (very common):
http://www.craigmedical.com/Drug_5Panel_DSC-Adulterant.htm
standard 6-panel test (most common, i think; adds mdma to above):
http://www.craigmedical.com/drug_test_6.htm
"multidrug" test:
http://www.craigmedical.com/Drug_5Panel_DSC-Adulterant.htm
nb. one might search that entire page for a certain tryptamine (one you mentioned in fact). or, for that matter, any number of tryptamines. if you follow my lead.