> weatherproof rugged speaker boxes, carryable

Check out 'garden speakers'. There are weatherproof and solid enough to
stand on in most cases, yet small and relatively inexpensive. They come in
all shapes and colors, from ceiling-hung ball to 'rock imitation with moss
covering'. Just pick something appropriate and add a carrying handle. I've
used such things in a project before, they are unbelievably rugged, but
heavy to carry. If you want it to withstand impact, look for the ABS mark
stamped into the plastic when choosing (the shop people won't know).

hope this helps,

Peter