Tank placement
I suggest fashioning a non-flammable insulating cover or shield around the baseboard heater just behind the tank. Connect a couple pieces of plywood together with 90 degree brackets. Line the inside with aluminum foil and some kind of insulator on the outside should do it. Make it so air flows through it from both ends so it doesn't over heat inside the shield. That should dampen any baseboard induced temp swings in the winter.
I would strongly consider an Apex to control your heaters (and everything else) if you can afford it. You should also invest in 2 high quality smaller heaters rather than just one rated for your tank. Watch the BRS TV You Tube episode on heaters to see why. Their episode on controllers tells you exactly how to set it up to control those two heaters so you're not relying on the sure-to-fail-someday thermostats. Even if an Apex is not in the budget, 2 heaters are better than one, especially if you get a temp controlled switch to control power to both. I really wouldn't scimp on this one. Thermostats are by far the most common cause of tank crashes.
You should also position a fan to blow across the top of the tank if it gets hot. Evaporation will cool it. With an Apex or used Reefkeeper (they're out of business but the controllers can be found relatively cheaply second hand) you can set it up to turn the fan on and the lights off if the temp gets too high.
With those precautions, I would go right ahead with your desired spot. You could even wait on the controller and fan while cycling and see how it goes with temperatures and adjust with what you learn. And don't rush the cycle!
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