That's interesting - it must be a UK/Ireland thing because it is an integral part of doing agility here!
OK tips -I have had a lot of experience camping at dog shows in a tent with no electricity so here's some thoughts:
1. Make sure your tent doesn't leak! Sounds obvious but we had this last year in torrential rain so I always have a tarpaulin on hand just in case to provide extra protection if needed.
2. Most people have an agility 'garden' which is a fenced off area next to or surrounding the tent/caravan. Can be really cheap and cheerful using the orange roadwork netting. I use puppy pens (the type that fold flat and are basically a line of wire panels joined together). They don't cost much, are secure and can be adjusted to the size of space available. Make sure they are high enough not to be jumped. I have ordinary beach windbreaks round mine, which stop the shelties barking at everything and also give them protection/privacy from the dogs walking past. Also does the job of keeping draughts out! You may have seen some very fancy set ups with caravans/campers but I use this all the time and it seems to work very well.
3. I do a lot of helping on the ring but people are very understanding and you can check on your dogs when you need to. Personally with a pup I would ensure he has sufficient exercise/mental stimulation early morning then you can pop him in his crate either inside the 'garden' or somewhere secure. Mine are fine by themselves in their 'garden' and are usually asleep when I pop over. People will also keep an eye if you ask them to as well. The neighbourhood watch system seems to work fine at shows.
4. Treats. Yes this is a tricky one and I will have the same problem with Angus (also a sausage lover!). I use the precooked cocktail sausages cut up. They seem to keep well enough and I have a cool box (not bag) with several ice bricks. Sometimes a kindly person with a caravan fridge may store milk/treats for you too but usually there is a local shop within striking distance of the showground to stock up on these essentials if necessary.
5. Take several coats! And wellies! And dog towels. You hopefully won't need them but at least you'll be prepared for the worst.
6. if your dogs are in the tent at night in crates then cover the crates. It keeps the dampness off.
Camping is so much fun at agility shows, it really is another level and the dogs seem to love it too. You'll have a great time. Look forward to hearing all about it. (I'm presuming that it is the weekend coming rather than the one just past?)