Feed in the tank.
Make sure that you are offering the prey at a temp that mimics live prey. A live mouse has a body temp around 100F so you need to get it a bit above that to make the snake recognize it as food.
I have always used water to defrost. After the rodent is thawed I give it fresh water as hot as it will come out of the tap to get the rodents as warm as possible before presenting them to my collection. I at one point used a zip lock bag but they always leaked so I stopped long ago. I feed them soaking wet and nobody has ever seemed to care.