You're better served by purchasing an actual contoller like the Apex or a AC Jr as it can montitor your tank summer & winter and control heat temps & lighting.
A clip on fan blowing across your sump will lower the temp by 2-3 degrees.
If the room your tank is in tends to heat up even more, you may have no choice but to invest in a chiller.
The camping ice pack brick things are a bad idea in the event they have a pinhole leak, you could wipe your tank out. No idea what the contents of those contain

You'd be better off freezing water in a zip lock bag or a clean soda bottle for days when the temp spikes.