You may wish to double bag the epoxy in heavy plastic bags and add dessicant to further reduce the chance of degradation.  Also note that the resin of many epoxies, especially toughened ones, will go through a phase change when the weather turns cold.  That is they cystalize and turn solid.  Several of the ones I've had do it during the winter but require only that they be heated to a hundred degrees or so to turn liquid again. The properties are not reduced.  What works well is to cover the resin container with a black poly cover wrap and stick it outside on a hot day.  The crystals dissolve and the resin turns liquid again.

For major structural parts, you may want to have the original manufacturer re-certify the adhesive.  What is typically done is that the viscosity is checked, the gel time checked and the Shore hardness tested.  What I've been told though is that if the gel time is still within spec, the hardness will be OK.  STill, it might save some dollars and sleepless nights to get a re-cert.

Dan Newland