I went ahead and pulled the trigger on an order of style #3 from LedFedy. May still have to do a little Dremel modification, but if so, the separate side "skirt" looks like it will make it easier. I'll need plenty of space between lens and star to accommodate my wiring, as I'll have four independent channels and my intended cross-section is this:
(1) 2" x 1/2" x 1/8" Aluminum Channel
(2) 1-1/4" x 1/16" Aluminum Flat
(4) 1/4" x 1/16" Aluminum Angle
(1) 2" x 1/16" Acrylic
(2) LED stars
(2) LED lenses
Aluminum/acrylic are off-the-shelf sizes, so all I have to do is cut to length. The angles will be glued to the flats with JB Weld, which has at least some thermal merit over regular epoxy. Then that assembly will be screwed to the channel with thermal grease at the interface, and removable should I need full unfettered access to maintain LEDs. I'm trying for fully passive cooling, and a small scale test looks promising; but if needed I can attach some heatsinks/fans in the inside of the channel.
Inside there will be clusters of four LEDs. One channel of 3W Cree XT-E 4500K's driven by a Meanwell LDD-700H. Three more channels of cheap 1W LEDs (460-470nm, 500-505nm, and 660nm) will be driven by LDD-300Hs. Some simulations on BuildMyLed say I can emulate just about any color balance I desire with this setup, including 5700K sunlight, or the DD Giesemann Midday/Aquaflora combo; with CRI up to 97 possible. LEDs will probably be attached with some silicone thermal glue I just discovered. All electronics short of the LEDs will be off-board, and connected to the fixture via RJ45 jacks and cable. There is some voltage/power loss due to 24-26AWG wire resistance but estimated at less than 1W, which I consider acceptable. Top it all off with a 48V 3A power supply, and a custom MCU/RF board.
Wish me luck! Now after all this frantic planning I gotta wait around a few weeks for orders from overseas. That may be the hardest part, LOL.