88f really aint that bad, especially if you are using Co2, and its not all escaping, and is replenished when it should be. While Ive never grown in a tent, from what I know, in sealed enclosure, it must be sealed to the point, where there is No Place, the Co2 can escape. If there is the smallest way, smallest hole, for it to escape, it will. But you say you have a monitor ect, so, if the monitoring is correct, higher temps, are actually recommended when using Co2.
At 2x 600w HID, in a 4 x 4 area, how well the plants do, will be up to the grower/genetics. That much light, in that area, is getting close to as much as the sun puts out, per sq/m
At its brightest, the sun puts out 1350w sq/m. and 2x 600w HID is 1200w, in a sq/m. Though, the sun doesnt suffer from getting weaker vs distance, like an artificial light.
MassMedicalStrains grows with 99% HID, and is coming out with both a 1000w Halide, and a 600w Halide, that are as close to the spectrum of the sun, as your going to find in an artificial lamp.
It is like the 1000w Hortilux BLUE, but is more powerful. Its the most powerful HID, there is, for the Spectrum. It is going to have a 6000k color temperature the sun, is 5800k. The Hortilux Blue, is 5500k. And I think they have discontinued the Blue. Blue was also $200. The 1000w, MMS is going to have, is $70.
But for what you have now, and with the Co2, and if it is being controlled correctly, and everything is dialed in correctly. Theres not much thats going to equal what you have, no less be better.
Also, remember. Some strains wont tolerate being blasted, and some will. And 2x 600w HID, I would for sure consider blasting them, in a 4 x 4. I myself, also start my seedlings under a 1000w HID, and have been know to start them under a DE 1150w Gavita, at 40 inches. 1000w HID either 20in, or 24. If I use a Hortilux Blue its 20 inches, and 24 if I use a 1000w Hortilux HPS.
As far as spectrum goes, nothing beats HID/Haide. LED may save some heat, and electrical consumption advantages, and not saying it cant grow some good weed, because it can, and in many cases, an LED, is the better choice, especially if one cant control the temps, or live in a very hot region. But HID/Halide has a huge spectrum, on both sides of the Invisible Range. Not just from 437nm-720nm.
The Hortilux Blue, and the MMS bulb both go from about 315nm-2000+. You would have to have multiple LED diodes for each individual nm, to get the same spectrum, as what an HID can produce. Which would be 10s of thousands of them.
If one wants to add UVA/B, add 2 Solacure 32w T12, for each 4 x 4 area, and 1000w HID. This bulb covers from 280nm-365nm, but is most powerful from 280nm-305nm. Its the only UVA/B bulb, that goes down to 280nm. It takes expensive glass to do this.
Agromax Pure goes down to 290nm, but is T5, 5/8 inch diameter, and has a much smaller surface area, and relies on a reflector, which YOU CANNOT REFLECT UBA/B EFFICIENTLY. The Solacure has a special chemical reflector built into the bulb, and is a T12, with way more surface area. T12 is 1.5in diameter, but will fit almost every fixture at the hardware store. Can be run from 25w-80w. But standard/default is 32w. It will burn your eyeballs out in short order, at 80w, and no protection, and will also burn your skin, big time.