VPN for specific web sites against censorship

Day by day the Web censorship in my country gains its strength. The obvious solution is to use VPN, but it slows down the connection and harmlessness of public VPN services can’t be guaranteed.

So I thought following solution out:

The router will access most of web sites in a conventional way, but will keep a constant VPN connection which will pretend to be one additional network interface. If I access one of censored web sites, router will pass the traffic through this virtual interface.

Is this possible with RouterOS? How to do that?

My router is RB2011UiAS-2HnD-IN, RouterOS v 6.30.2.

Make an address list of all the servers that you want to access over the VPN and use routing-mark in mangle.