if the client isn't allowing you the option to use a vpn, then they acknowledge that will have to spend more money on travel. after all, the point of the vpn is to allow remote network access.
so, have them pay for your travel to their site. or buy a PB license and install on a non-vm machine ( i assume they will provide a remote desktop type of access?) if they have access to your source code.
I go through this a fair bit with customers, and usually they end up providing vpn access when they are presented with the alternative of spending thousands. the guy saying that they will not provide vpn usually reports to the person that signs the checks.
I know, some companies have strict policies for their users. A bit ironic though, that if a company doesn't want to allow internet connections, they still decide to put everything on the cloud. (which needs an internet connection).
regards.
regards.