Hi!
Maybe this is just a question, maybe feature request. It would be great to have a VPN solution for mobile users that could work from any place: from NATed networks, from highly firewalled networks and so on.
PPtP does not allows to work from classical NAT (without VPN natting modules).
IPSec seems not supported from any place too, some NATs and aome firewalls not allows to use it.
Maybe some solutions like OpenVPN could work with Mikrotik?