AHP, not only is it mountainous and arid but the Turks created a dead zone between the Byzantine border and their own heartlands which made it worse from that angle. Combined with the Turks own fighting style and the Crusaders stupidity its not surprising the both 1101 and 2nd crusade came to grief in Anatolia. However the 1st and 3rd crusade crossed reasonably successfully, so it can be done. The Turks learned from their experiences with transiting crusaders, I wonder what are the possibilities arising from the crusaders learning from experience as well. What I'm thinking is crusaders carrying more supplies after hearing about the privations of the 1st crusade, and choosing the best route on the advice of 1st crusaders and Byzantines. Also perhaps using the pilgrims as labour to fortify laagers when the Turks threatened, in order to minimise losses and give the crusader cavalry an anvil to hammer against. A victory like Doryleaum could give a crusade much needed breathing space to make a fast transit.
I've been reading about Egypt, and the three invasion routes to get to Ciaro to get a stranglehold on the country. If an army goes from Alexandria it has a good base but faces a longish marcha cross the desert only to arrive on the wrong side of the Nile from Cairo, not awesome. If going through the delta all the river and canal crossings are very easy ways for a defending army to stop an invasion, 2 crusades into egypt were stopped this way I think. Going through modern Port Said ois a short march direct to Cairo itself, but there is no way a base of operations could be set up on that shore which make that idea difficult. If an army can work around those problems capturing Egypt is easy enough, but holding it is another thing entirely.
'Holding it' is a major point about Outremer, Oman calls Edessa an Armenian state where the warlike locals filled out the ranks of the Franks army. But the Syrians of Outremer proper were not warlike and didn't beef up the army so Outremer had to rely on imports and the odd crusade for manpower, which is untennable. This is where my little mental fantasy of 1101 and 2nd crusades reaching Outremer intact and exapanding it, capturing Damascus, falls flat. Unless the crusaders can fill the ranks of their army with local christians Outremer is ultimately untennable.