I'm confident that a significant part of your issue is indeed line length. It is tricky to get good, consistent pours with 5ft lines even if everything else is dialed in well. Been there, done that and had similar problems with the first glass being more foamy. When you first open the tap, the beer wants to come out at a higher velocity which causes foaming when it hits the glass. Now I use 12ft of 3/16" line on all three taps. It slows the beer down some and I enjoy much, much better (and consistent) pours.
Line length, warmer tower, service temperature and pressure are all inter-related and all play a part in the issue you are having. What are your temps and pressure?
To blow cold air up into the tower, you can rig a computer fan powered by a 12v wall charger. Simple, cheap and it moves plenty of air.