Help! I'm going on a lousy camping trip!?

I'm 15 and my dad wants to take me on a camping trip to Big Bend State park(TX) over spring break. But this isn't any regular camping, this is supposed to be . No campsite. NO toilets(ffs...). NO showering. For 5 days! Just Hiking....In the middle of a desert-like place. I'm gonna have to take a crap somewhere along the line. Its probably going to be behind a cactus or something... I AM NOT LOOKING FORWARD TO THIS. Any tips to keep myself from going insane?