Pea...I bought a soft one for my trip down last year...and it did fine. I do agree....put luggage in a big bag to avoid any water seepage. The hard carriers do take up space when you store them...but you can always use it during the winter as a bob sled....
This is what we use...beach chairs, toys, go up top first...if we pack luggage...just for precaution we put it in trash bags...but this thing is really waterproof! It's not quite as flexible as the cheaper ones you can pick up at Target, but you learn how to pack it...it's a challenge we have conquered and have mastered!!! We haven't had a bit of a problem the last few years when we've had to add a porta-crib, high chair & sometimes even a stroller!!! And yes...we always pull our vehicle out of the garage and pack the top from the driveway...we can almost always pull back into the garage...but sometimes NOT!