I can see that on it's side with the doors opening down out of your way or up and propped open. As far as propane if done correctly there is little danger. A cooker that big is going to use lots of gas to keep it all hot though.
post more pics as you build it out......looks like a good project. There are a few vertical gas cookers out there and that cabinet looks like a good one for that in the upright position. Build the right gas chamber for it to sit on and you might have a smoke house in the making.