Sorry. Just reread your question. If you are using the hotspot feature of the iPad, it has it's own access to the internet and doesn't go through the router, except for access to the network at the end of the vpn.
So, unless you have to turn your iPad in every now and then, you can pretty well do what you want. HOWEVER, your data use could be monitored if someone else is paying the bill, and the ISP could give the information as to what your SIM card has been used for.
Best bet is to simply buy your own tablet if you want to surf independently of your company equipment. You don't have to have another iPad. There're plenty of dirt cheap ones around if all you want is a browser.