In theory an SSRI like Tramadol mixed with a psychedelic should not cause serotonin syndrome like many worry unless the psychedelic is also a serotonin reuptake inhibitor or MAOI of some kind, like AMT or 2C-T-7, but 1) We don't know for certain that 2C-P isn't an SRI of some kind, and B) psychedelics lower the seizure threshold (meaning they make you more likely to have a seizure even if you're non epileptic), and Tramadol lowers the seizure threshold a lot so this isn't a good combo.
There aren't many things Tramadol is very safe to mix with to be honest, since many drugs out there lower the seizure threshold and can result in some nasty (even potentially fatal) convulsions when combined with Tramadol, and psychedelics have certainly caused this for many people - even if you don't have a seizure, sometimes you can feel one coming and it's a very unpleasant feeling like you've been poisoned and don't know what's going on, so it's absolutely not worth the risk.
If you wish to try such a combo replace the Tramadol with a different mild opiate like say Codeine - I've combined poppy seed tea (which contains opium) with 2C-P before and it made for a very interesting and powerful experience.