If you're worried about accuracy, PTO would be as robust as PS with Lacerte under the hood.  But if you like form-based input, PTO would probably not be your choice.

Private VPN would probably be your best option, notwithstanding the cost.  Because tax software is resource intensive, you'd want to make sure you have sufficient RAM and good hardware for the server to run virtual machines.
 Lag may be a problem whether you use VPN or remote desktop, depending on bandwidth, so you may need to do a bit of experimenting.