Hey John lovely dio. The figures are really, really nice. Some of the best I have seen and go perfectly with this dio.
You asked about the AT gun......I think it works but it is to close to the Tiger. If it was me I would place it further south of the tank , more towards the parallel side. This also gets it away a little from the figs. If you go towards the corner it will look to even.
On model Mojo - I hate it when it disappears but it always comes back. Mine is back at the moment so I feel for you