I know matrix cubes are not the cheapest thing in the world. My job that im currently designing requires over a 100 of them. Needless to say im not gona use them cause the cubes themselves would price the job over budget. For large jobs such as yours I use commercial grade poly tubes that they use for drain basins and culverts. They range in size(the ones im using are 2' in diameter). Now these are the ones that are ribbed on the outside and smooth wall on the inside. I will get a 20' section and cut them down to what size I need. I then drill 3/4 inch holes through out the pipe. In my opinion they are stronger than the matrix cubes and allows just as much open space for water. Once they are in I then place larger gravel and top with smaller. You will have no problem driving over basin. Now the price difference is what us pond builders like to see, my way costs a third of what it would have been if I used the cubes. Don't get me wrong the cubes have there place, however on large jobs where budgets are tight there are always other options. This is my Christmas savings hint on the year for those who want to use it lol..
Fyi on a personal note.. I was born in Goldsboro NC. Miss that place loved living there.