Unfortunately, I cannot offer you a singular treatment approach as it depends on the symptoms and severity. The range of options vary from a topical steroid and antihistamines for skin rash and itching to oral steroids when the symptoms are more systemic and severe. I would advise wearing protective clothing - long sleeves and long pants, washing hands and if you notice a rash then seek medical evaluation and assistance soon rather than waiting to see if the symptoms will progress. 
Good luck and enjoy your trip. 

Sincerely, 

Monika Korff, MD

Assuming you are allegic to poison oak (and poison ivy or poison summac), the treatment would consist of avoidance (if possible), a corticosteroid cream if a rash occurs and (if warranted by severity) an oral corticosteroid medication such as prednisone (or others)

Hope this answers your questions