Can I make a pineapple upside sheet cake in a jelly roll pan? Are they roughly the same?
I would not try it! The sheet cake pan size is most likely much larger than a pan you would use for an upside down cake and the edges are not very high--you could have a sticky mess of butter and sugar on your oven floor. Depending of the size of the cake, I'd use an 8-or 9 inch cast iron skillet.
the jelly roll pan is too shallow. a 9x12 or 14 casserole will do, or if you have hotel pans, a 200 or 400 will be more than adequate.
I have, and you can. However, know that the topping for PAUSD cakes is notorious for overflowing and creating a sticky mess in the oven. Place a sheet of foil larger than your half sheet pan, its edges folded over a couple of times (you'll likely need to use two lengths of foil and join them in the center) underneath your pan. Also, you baking time will be significantly reduced because you've spread the cake more thinly over a larger area, so set your timer accordingly. You can always bake it longer, but it's extremely difficult to unbake it.