I do not have the law in front of me to cite verbatim, but if the goblin has your property and you have no realistic options to regain possession and they have not left your sight then you can indeed shoot them in the back. I don’t think this is an “after dark” issue either.
Before using this information it would be wise to research it though.
It's not. Only simple theft, as opposed to burglary or robbery, and criminal mischief, are subject to the "during the nighttime" restriction in the Texas justification for use of deadly force part of the Penal Code. But even that doesn't consider the recovery of property aspect.
I'll get the link to the law later and post here. I'm not on my own computer at the moment.