what you could do is in the nearest town train ONE peasant then send it to the the other faction, the caravans tip was from before 1.10, also you can design your own 'pioneer' unit with a 'pioneer pack' so that you can build towns where you want, not just where you are given a pioneer.(this is another way to pass the barrier as influence will pass the barrier, it is just that teleport is not available so can not teleport past the barrier
the boats are gifts from the LAST (tarth & carrodus?) two factions before you got to the footprints,
when you recieve the first shipload the troops you are given onto it then sail it to the beach near tarth, unload one or more troop(s) onto the beach and walk to tarth, you will be given another ship and three more troops load them onto the ships
(additional option, but btw if you want to you can also add a 'hero' to one of the ships and sail it to the southeast (bottom right) island and explore it(you should find a scroll that adds a new spell for reliasbut if you do not have a 'hero' then you will not get the spell),
then sail the ships around the bottom of the map and up the left side of the map to the beach next to the fireshard near the blackwall, and it is a very good idea to have several(at least 3)squads(third from left group size and eight indivduals in the squad) with the best weapons/armour that you can make do the final attack on the empire dragon group that will END the campaign.
you might be able to win the campaign with a smaller force, but might lose, I have used 6 squads of hammer armours and not lost a squad an suspect that three is near the minimum.
harpo