I put clones in solo cups and then put them in a cardboard box.
Same here. Milk crates work well too and you can fit 5 in. I usually crumble up some newspaper as packing in between. Those 4 slot cardboard drink holders from McDonalds work well also.
I think a lot of these details are different for everyone. Just be creative. If you are in a place where being spotting is a concern, do it at night. If you live in the middle nowhere, hell, you can prob just walk right out your back door into the woods.
Also, this is very important. I think Balzac mentioned this once before, but it's one of those things that can't be stressed enough...WATER. You don't want to put yourself in a situation where you are hauling water from home. Now I'm not saying plant on the bank of the local swimming hole, but plant somewhere close enough that making several trips with buckets/cans/jugs, etc, will be feasable. Trust me on this one, I've been there. Best case scenario, you can fit two 1 gallon milk jugs in a book bag. That's about enough water for one medium sized plant for a week at the most. Any water will do as long as it isn't overly polluted. I used water from a small pond last year. Remember, the times when your plants will need the most watering will be when it's really hot out, so be smart. Limit the distance between your plants and your water. I like to do it early in the morning or in the evening when it's cooler.