Finished a project. Squirrel cage blower seemed to throw the air everywhere. It takes 33 minutes after turning the fire off for the thermal switch to turn the squirrel cage blower off.
With my quieter 4 watt total, 120mm fans, it takes just 10 minutes to cool the heat box to the point the thermal switch opens. Seems like it's 1/10th the power, 1/10th the noise, and 3x as effective. Ima patent this when I get a round tuit.
I don't get why these fireplaces come with $200 ineffective blowers that are too noisy, when they could come with $20 worth of case fans that are way better.
I did have to drill mounting holes in the grill that are not externally visible to mount the fans. Then coroplast on the outside and duct tape to seal the small strip next to the fans.
EDIT: The fans are so effective that it can cool the heat box down enough that the thermal switch opens while the fire is on. This is something the standard blower was never capable of doing. Once the thermal switch turned on, it ran the fan until 30+ minutes after the fire was turned off.
I might even put a speed controller on there so I can turn the noise down even more, and that would put less cycles on the thermal switch.