The solution to your temp control problem is (wait for it) a thermostat!
Your hydro shop should have ready-made units that you can just plug in and hang at plant height. If they don't or if you're feelin' cheap, you can convert an old waterbed thermostat, but you'll need to add a relay to swap the logic so it will turn things on when the temp setpoint is reached instead of turning things off. Let me know if you need that wiring diagram and I'll draw it.
To do clones reliably, you'll need a small clone box with light and a heat mat. Thermostatic control for the clonebox fan is a good thing, but not essential, unless ambient air temps are very low and the box gets too cool to give you strikes in 7-10 days. 40mm rockwool cubes are a good size for cloning. Use rooting powder instead of gels. Gels wash off too easily when watering- powders form a paste which stays put better. Gels also can support pathogen growth if stems are dipped in the main container of gel instead of a small amount portioned off, used for a batch of clones and any excess discarded.
You'll want to establish another, smaller grow tent to maintain a few mother plants. Part of the reason your clones didn't go so well is because you did your cuttings from a plant which had been in flower for a couple of weeks. Call yourself lucky for getting one to go. It'll be a lot easier when you get cuts from a healthy mum plant in full veg mode.
I think you've discovered that you vegged a bit long, resulting in plants taller than you needed and could have pruned back lower branching a lot more a lot earlier. I think you'll have better performance in your limited space using SoG instead of FIM, the latter which results in fairly large, bushy plants- not ideal for indoor growing, unless you must keep plant numbers low. SoG ops grow many more but much smaller plants, effectively only growing the top cola. SoG is a technique which better suits limited space and indoor lighting and ventilation limitations.
Did you get a nutrient meter yet? If not, spend the bucks on a Truncheon. Has all common scales like EC, CF & PPM, no moving parts, no digital display to fail and is totally waterproof. You'll only buy one Truncheon. Mine is now 7 years old and goes through a set of batteries once a year.