Don't get tempted...
1. Meds used for other protocols, notably benadryl and valium, are pretty potent psychoactives, along with atropine, Zofran, gabapentin, and epi. Like it or not, you are already giving "psych meds".
2. Using "psych meds" (meds for psychological or, more precisely, behavioral impact) in the field is generally to control hallcinosis, and to act as a chemical restraint. Each has legal moral and pharmacological implications, as well as potential misadventures because someone's label ("Psych") was treated instead of a potential underlying cause.
In fact, many cases of "crazy" people have turned to to revolve around undiagnosed hyperthyroidism, serum glucose swings, overuse or other misuse of meds (including OTC vasoconstrictant nasal sprays like Afrin and others), other metabolic or neoplastic disorders, and hidden drinking or drug abuse. Your eval could be the one that puts the pt on path on recovery. Of course some aren't crazy, just sociopathic, then I get 'em.
Our local EMS Council rules do not slice that thinly, I think the parameds have to call for info or permission. Calling the pt's treating facility could make a huge difference in tx.