Another person to check with is Tony Killip. His website is OurKitesFly dot com. He has been flying the 30 foot Clown Fish for several years now. Tony is also a member of this forum, so you could hook up via a PM ... akillip.
As to sand anchors: All I've ever used is Gomberg's large (3 foot sq) sand anchor. Read the write up (http://www.gombergkites.com//F-ANCHOR.PDF
) that Gomberg provides in each sand anchor package and follow those instructions. I've flown 190 sq foot kites with inflatables off the 3 foot anchor with no problems. And, I've seen that same size kite sailing across the sand with that anchor (full of sand) in tow. Technique makes all the difference.
Line size? I'm conservative, so use 1200 lb line on the main lifter if it's over 100 sq ft and 450 lb line on the inflatable. Look at Gomberg for good line ... don't buy cheap line. The 30 foot Clown Fish lists for $1000 ... add in another few hundred for a lifter kite ... seems silly to save a few dollars on the line that is supposed to hold them in place.
I purchased a 30 foot Clown Fish last fall, but have no experience with it yet. So, maybe we can learn together.