Actually, if SC heat is your problem, then Dirty drives are supposed to be (slightly) better than clean drives. Thrusters are not contributing to the heat in SC, but their power consumption will - and clean uses more power than dirty. The niche for clean thrusters is smuggling and other "dark" ships that need to operate in real space.
PP - if you can tolerate the heat, armoured is usually considered the better option. Improves integrity (and the PP is the only thing you can't repair in the field) with slight improvements in power generation and heat. Armoured G5/thermal spread usually gets 0.32 efficiency.
That brings me to the next pooint - not only switch off anything you don't need, also downsize or D-rate anything else you do need. That Beluga is fine with 6A thrusters - you're still below optimum mass there.
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You probably could step down to a 4A PP - but that might become a problem if you aren't very careful with power management on planetary landings: you're landed, so thrusters are off, power on SRV hangar, leave the ship --> all ok.
Now the ship takes off on autopilot, which means thrusters are activated... power failure, everything goes off, boom.