I made a fixture for a 20" wide (24" deep) tank with those sockets attached to a rail of aluminum strap from the hardware store. The 3x3w bulbs I have used, despite the bigger heat sink, still get CRAZY hot and lately have started to buzz and hum. I am going back to 3x1w lamps for that fixture. YMMV, your bulbs might have better electronics.
Also, heat plus wires plus electrical tape always equals fires in the long run. It looks like you did a pretty good job of cutting that all to length but it would be more safe to pull all that tape off and replace it with those plastic wire nuts. Seriously. They're designed for that kind of thing, and it's not like you have to look at it. Electrical tape is not for insulating AC loads. It's not making it more waterproof, it's just slowly leaching chemicals under heat. If you want a more streamlined wiring look with some amount of real weather proofing, butt connectors and heat shrink are very easy to learn how to use (keyword:youtube on the googlebings). But if you looked at the back of those sockets you know it's just a piece of shiny cardboard so there's no such thing as waterproofing it, so you may as well just use the nuts. At least if the wire nuts catch on fire there's a company your insurance can sue.