Margat was on the coast and seems a bit far to be the tower, where other authors are sure the tower was built on Mount Silpius near Bohemond's camp. The history of Margat seems to cancel it out as a candidate but I did find an interesting account of its fall from an Arab perspective in the Third Crusade here. There do not seem to be any accounts of the First Crusade from an Arab eyewitness perspective but some later Arab writers like Ibn Al-Athir wrote about the First Crusades and a biography of Saladin. Also interesting to read are accounts like Usmah Ibn Munqidh's autobiography about life under the Frankish occupiers here.
Making the search for Bohemond's tower harder is that most of ancient Antioch is buried under the modern Turkish city of Antakya and there seem to be little that has been uncovered. However it does make more sense to build a watchtower near the city since the Crusaders had not lifted their siege and remained there for about a year and a half.
I found a nice map of all the Crusader forts in the Middle East. I don't know how accurate it is but there are also some very good books on the Crusades worth buying besides the Krey book. I have had a good look at a book called The First Crusade: A New History by Thomas Ashbridge. It looks very, very good with maps of the routes they took and ancient cities so you can see the layout of the battles. August C. Krey's book is also excellent but an older book and includes some funny details like calling the Arabs 'barbarian hordes' where Anonymous clearly hasn't but he has broken up the account in Gesta with many other eyewitness accounts to give you a chronological history from various points of view. If you just want a copy of Deeds of the Franks, Oxford Medieval Texts has an excellent version with Latin on one page and the English translation facing it. It is pricey but you get the assurance of it being of the best quality in scholarship.
One more link I would like to post is a photo of the Cilician Gates which is the mountain pass that Anonymous describes as narrow and dangerous. The Taurus mountain range which they had to pass through was very difficult to pass indeed. Here is one photo and here is another rather bleak looking mountain.
Although Anonymous does not say as much, after Baldwin took that town from Tancred, Tancred returned to the main Crusader army but Baldwin did not. Baldwin headed east and carved a kingdom for himself in Edessa. Judging by the accounts of Fulcher of Chartres, Baldwin was prepared for all kinds of back stabbing to carve out a kingdom for himself. Should I be using judgemental words? Why not since this is not a academic or 'scholarly work'. Anyway, while I was trying to find out more about the tower, I came across all kinds of information as to what lies ahead of the Crusaders or later Crusades. They eventually won Jerusalem but at what a cost in human suffering.