fixtures would work very well since you have center bracing. You could obviously mount each pod over each hole.
However, with florescent lighting, I don't think you would see much of a shadow. Light diffuses rather quickly as it hits the water, so it wouldn't be that noticeable. However you might have problems growing anything high light directly under the brace.
The radions are really nice - but also pricey. There are cheaper solutions out there that will give you the same results. A lot of folks have been having great luck with the taotronics led
fixtures on ebay... at about 20% of the cost of the radions.
Best of luck!