Credits: The original PBO used for this post was obtained from someplace that I don't recall. I simply created the tutorial to make it easy for everyone to understand.
This method lets you create custom content in the editor and make it into a server side pbo. All items can have simulation enabled on them.
Make sure you have the Exile Eden plugin from the Exile Downloads page in your @Exile\addons folder. Personally, I created an @Exile_Edit folder and put it in the addons folder of that so I could just load that instead of moving that Exile Eden plugin every time I wanted to play.
Start the editor and create your addons. I won't go into how to place objects and move them around, etc. You should know how to do that. Please don't ask how to do that. Create a new thread for that.
Once you're happy with what you've designed, go to the File menu up top and save your creation so you can edit it later.
Go to the "Exile" drop down menu and select "Save initServer.sqf":
On the window that pops up on your screen, click on Copy:
On your desktop, create a blank file and paste the contents that were copied to your clipboard.
Save that file as yourcustom.sqf (Pick an appropriate name for your content).
Download this pbo: https://www.dropbox.com/s/32v7i81loel8l2m/a3_custom.pbo?dl=0 and extract it to your desktop.
Copy yourcustom.sqf to the pbo's a3_custom\mapcontent folder.
Open fn_init.sqf, found in the pbo's "init" folder.
Edit the lines to include each addon name. An example is included in the fn_init.sqf:
 execVM "a3_custom\mapcontent\yourcustom.sqf";
Repack it and upload it to your server's @ExileServer\addons folder.
This puts your addons serverside to players don't have to download as much and it protects what you've created. You can also do the items around your traders this way too.
NOTE: If you want simulation enabled (ie: you want a working light), the double click on the item you place and select "Enable Simulation". Be sure to enable simulation on any buildings you place or else you won't be able to open the doors. Enabling simulation lets flags flutter in the wind, lamps work, gates open, etc.