Mr. Elric's supply request brought a thought to my mind. At home, there's a branch of magic called Transfiguration which is turning one object into another. I do hope none of you overreact to magic, a mind wiping spell on all of you would be tiring. I may be able to make things that are desired or required, though it's not a specialty of mine.
In addition, if anyone has a decent map of the surrounding area and towns, I can... I believe the Muggle word is teleport?
And this may be a rather silly idea, but have we considered something like tying a string to an animal and sending it through a portal? It would at least tell us if the other side is going to be somewhere absurd like in a volcano or 50 miles above the ground.