The lack of support is not because Player is free (which it isn't for commercial use, by the way). It's because of the features that are included in Player vs. Pro. Player is limited only because custom networking is a feature of Pro and not Player. You might be able to to configure custom networks with Player, but you're going to have to know how to do it with the command line and that's not really well documented. And if Player should reset things, well, that's likely something you'll have to live with.

My suggestion: if you want custom virtual network configuration that's fully supported and easily configured, use Pro and not Player.