get a CFR rack.
Bungees and home made junk just dont cut it. You spend 5000$ on your sled and 800$ on your skis, so why cheap out and only spend 15$ to put the two of them together.
I have seen just as many broken skis as i have seen home made racks.
The pics posted above have the skis runnign right up along your seat, the make riding the sled very difficult, and when the ski is inline with the tunnel, they tend to make getting stuck worse.