using a large ice pad to keep temp down?

Preparing for the summer months i pose this question to those experienced brewers. I have a cold closet that stays about 4 degrees lower then the ambient room temp during winter months. 72 room 68 closet!

However, with summer months i think ill have a 1 to 2 degree difference. I have an ice pad that is large enough that you can place a ropak bucket on it and i covers 85%. It's a flexable ice pack.

What would you risk by setting ice pack under the bucket or wrap it around to drop temp for fermentation?

That's possible, or consider a tub of water to set the fermentor in and occasionally drop in fresh frozen 2 liter bottles of water to keep the temp down.