Shit Dude....., you've got (maybe) a good spot. Soil is great, but has to be treated properly. Check list. Good drainage. Yes. River bed carried all the nutrients down stream. Long haul, & money's tight. Live between somewhere & nowhere, as I do. First concern is direct sunlight. Counting direct & ambient, are you getting sufficient sunlight. Next is an easy carry water retention product. Silt drains to fast. What you are looking for is something that nutrients & water will cling to... long enough for your root system to absorb. A 10 to 12 inch deep trench on the upside base of each plant, filled with cheap, lite-weight peat moss will gradually feed your plant. Your town has a local nursery, that's where you get peat moss & fish emulsion, and liquid seaweed would be cool, along with greensand. Dried cow shit will hold water, also, whatever. At your local Grocery store, get some molasses, & Epsom salt. The salt will provide the minerals needed. Ashes from a wood fire will help a lot. Good luck.