Let me put down two different options regarding the port a cot. I have done both.
Option 1 - no port a cot. Lets see, more room in the car or trailer, but where to put the child for a sleep. Night not so bad, but in the day, when I layed my daughter on the bed, she would get up, and up, and up, then crawl through the zipper outside, or get into all the bags, or climb up onto our bed or do what ever she pleased and I would spend an hour of walking in and out of the CT to make sure she wasnt in to anything. Most of the time - NO SLEEP - ROUND 1 TO BABY - MOTHER STUFFED!!!
Option 2 - port a cot - a little less room in the car or CT, but a child that gets put down for a day sleep at 1.00pm, mother walks out with baby crying a bit, walks to fridge, gets out
and sits for 5 mins until baby settles down knowing baby cant get out, crawl out, climb up or hurt themselves. All this = refreshed mother at 3.00 when baby finally wakes up. ROUND 2 TO MOTHER - BABY HAPPY AND SLEPT WELL.
Up to you but I chose to take a port a cot with me with both kids. Pain in the but - but worth it for mums peace.!!!!
Be happy - take the family camping.