You could rent a lot of storage space or buy and build a small
storage shed for the same amount of money.

If you're a half decent carpenter and you throw enough 2x4's at it,
you'll probably end up with something stronger than you started with.

If you use 1/4 bolts with fender washers and (or) #12 or #14 wood
screws and pre-drill the holes (and not nail anything together) you'll
have something stronger than the existing framework.

I bet your existing wood is full of splits because of the hack job
that is usually done when cutting rafters and pounding over-sized
nails in.

Do yourself a favor and make sure each and every rafter space is
ventilated out to your soffit overhang. Don't stuff the insulation in
there - let it breath.