If its not court related you won't be observed. If anyone tries tell them you can't pee with someone watching.
Go to the dollar store and pickup a bottle of travel shampoo or something similar and rinse it thoroughly. You only need 2 ounces. Get a thermometer so you can practice getting the temp right. If you buy synthetic urine it comes with a small bottle and a temp strip.
None of the detox or masking kits work. If you want a backup plan drink about 40 ounces of gatorade the morning of the UA, pee 3 or 4 times and use your midstream urine for the collection cup.