We used a small aluminum cell from Jegs on a diesel powered project recently. The only thing we had to do was remove the foam from inside the tank. We were advised that the foam would degrade and make its way through the fuel system. If you are worried about extreme angles, I would invest in a check valve for the vent line, that way fuel won't go pouring out while you are up on your side. The other thing to watch for is the material used as gaskets on some cells. Some manufacturers use materials that will degrade when exposed to diesel, this was one of the reasons we used the jegs unit (it was also really inexpensive).
For the pickup, you need something that is flexable. In oval track cars, we use a piece of flexable hose, with a weight attached to the bottom end of the hose. That way, whichever way the fuel swings, the pickup goes with it. Just have to make sure you use something that will not gall up the inside of the tank, leaving little shavings in it. As long as you keep enough fuel in it, the pickup should follow, even better when you put it on its side like that.
Hope this helps