My research about RB1200 as VPN solution: Mikrotik RB1200 as VPN Solution
You can find wiki entries about your setup:
Wiki:Tunnels
As example:
PPTP VPN - multiple ADSL remote locations to Cental Office
Branch1(Mikrotik VPN Client) → Central Office(Mikrotik VPN Server) ← Branch2(Mikrotik VPN Client)
Also if possible you can switch your VDSL modem in bridge mode - for more convenient remote control of Mikrotik.
for more convenient.
VPN Server can bind on any port.
As raz mentioned you can create oVPN tunnel on 443 port.