I like your plan. In fact, I'm going to show hubby the pics and see if he won't do something like that for ours. Mine keep getting out of the yard. So... the cats won't or can't get out over the netting since it's curved inward? I guess they would have to hang upside down and hoist themselves up uh?
I'm not sure which state you are in, but if you are in Victoria look at your loacl council's website (and if not, goto
http://www.melton.vic.gov.au ) and check out the "Cat Proofing Fencing Guide" or whatever it's called. It's a state government publication that gives you step by step instructions on how to build it. We used it as a guide and just altered a few things to our liking (i.e we got the netting from catnets.com.au which was different size netting to what they said to use). It's a lot easier to make than how it's written. The hardest part was sourcing the steel poles at a reasonable cost, the rest was childs play!