Eric:

You can plant them together with no problems. But realize that you have room for only two plants of each. So I hope that you're not planning on growing anything else in that area. You can expect about 6 nice fruit of each, maybe 10 each at the most. Good luck!!

The Fruitnut

I would use your native soil, but make a hill to plant your melons on. Different melons grown together may effect the seed produced but not the melons. Allow about 6 feet spacing between plants and keep them well watered and fed. You will need plenty of heat and sun to produce good melons. Al