I've been setting them outside in the morning, and bringing inside at night. The day temperatures are into the 50s and 60s, for the most part.
I wasn't going to set up the "wall-o-water" units but under the circumstances, I think they are the best approach. I took the soil temperature, it's 50 degrees, so technically warm enough to plant. I will leave these units in place for 2 days then plant tomato plants. There will be some extra plants to try elsewhere. The arrangement is not planned. My garden not only has an "organic" soil/pest management/compost/plant food philosophy, but apparently has an "organic" constantly evolving shape. Not planned that way, but it is what it is. Nonlinear, no straight edges or 90 degree corners.