I'm planning to be fairly easygoing about this--I figure if my pcs have the cunning to get hippogriffs or dinosaurs as special mounts or find something to bring with them I should simply applaud their resourcefulness and let the dice and encounters speak for themselvs. Any thoughts though? Any warnings?
Handle it any way you like - just be aware, that they would have a very hard time to take the mounts along later, into SoS and beyond. Very hard, if not impossible to stow them on the Sea Wyvern ( they won't fit through the main hatch, which runs down straight into the common sleeping- and mess-area anyway. No hatch from there down into the hold, just a steep staircase...... (bad ship design - but who actually cares for a "working" and sensible ship except for those with a maritime penchant ?). Not to mention adequate provisions for the hungry carnivorous beasties...
And stowing them on deck will make sailing nigh impossible - the cages will get in the way of ropes, lanyards and halyards being pulled or eased, beams and yardarms getting shifted and general procedures at deck ( Our group added a capstan - a vertical winch - for realism's sake, otherwise it would be impossible to raise the anchors or the mainsail, which made it even more crowded on deck ).
Plus, there is not too much advantage or plot-breakage to be gained from mounts throughout the STAP, except perhaps for bypassing a certain humonguous crocodile.
And one might have to weigh the risk of haing one's trusty hippogriff mount killed from underneath oneself inflight by a passing vrock or wyvern.....
So basically, IMO, getting "special" mounts will be waste of time - unless your group has fun doing so, in which case, go for it.
or get a dragon and ride the air.. ;)
A few thoughts:
1. Apparently according to Stormwrack a cog has an open hold plan. Not exactly wonderfully seaworthy but magic might help with that. I might make one of the available pirate ships a cog instead of a caravel.
2. There are going to be at least 3 flying mounts. However I was looking up the rules on this and apparently flying mounts can't be encumbered heavily for too long and so won't give that much advantage (though enough of one for my pcs to probably go for it anyway)
3. Some parts of the journey will be long enough they'll have to land even when travelling.
4. Upon arrival on the Isle they'll still need to help the survivors of the ship, and there won't be enough flying mounts for all.
5. Only one of these mounts will be able to descend into Golgismorga or do the dungeon type adventures at all.
I think I've covered the bases and can still run it effectively with these.