I think the idea from SketchUp is Hassle and Support. I think it's legal and proper what you are doing and I think Google understands a small businesses need to save costs. I believe that they see it as a hassle that you have to go through to save that money, ie employees moving about to complete work. but in reality you could do everything Pro does (with the exception or a north arrow and Google Maps grabs) with plugins or by taking .skp files to other software. although you won't get Layout 3 which is also a very valuable addition. By purchasing one or more of the Pro versions you're eliminating your hassles and showing your support for the software and the platform.
I would feel more comfortable with you situation if only one employee was doing the exporting with pro and other users simply used the free version on their system. but in my opinion I think you're ok right now. I don't know if we'll get a Google Rep in here to publicly comment on this, but there are quite a few here and I would think they will see it. so we may get an official answer...
welcome to the forum btw and we'd love to see some of your work.