Either might work. Been a while since I ran a dedicated server under A16 but what little testing I could do solo this might work. If it does or does not let me know.
*** Edit ***
Just in case it wasn't clear the intention for this fix would be to add the giveselfxp command to the allowed list of commands for anyone on the server (permission level 1000 being guests/players). If successful players on the server should be able to use the giveselfxp command as if they were the host.
Sadly I haven't found any way to give xp to another directly via the console or as the host/admin.
If you don't want to give the command to everyone on the server you can use the permission system to set access to the giveself xp command to a higher level and then add/remove players from that permission level as you see fit during play. Depends on if you're just running with friends or hosting a full public access server.