Trail bombs are easy to avoid if you are farther way when they trigger, or are already moving. There is another spider bomb in the forest that I tried getting a summoning doll to take (unfortunately, one of the patches removed the dolls' ability to open trapped containers). It triggered the trap fine, but the spider mine veered off and took out a frog.
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Trapped containers are a little trickier. Leave one character at the hermit's cave (etc) and stand by the trapped cocoon with the second. Pause the game and open the cocoon, then switch to the first character and enter the hermit's cave, to teleport the second character away from the trap.
The key for that chest in on one of the teleporter islands in the burnt forest (north east section). There is not much of value in the chest, though.