I started the escort mission on level 46 (mid forties are common for the end level of FoV/DKS; not sure what the low end of the range is). I paused the game right away to reassign skill buttons (to match the configuration I had them before), and to re-equip the armour I had on at the end of D2:ED (with +40% Offence and +40% HP bonuses).
Quoted from another topic, I described how I did this section in the spoiler below. Dragon dash (left shoulder button on Xbox, right mouse button on PC) may have helped if I had remembered to use it. Also, I didn't realize you get another skill when the zeppelin captain tells you they can bombard a target you select (thought it was automatic, since shortly after mentioning that they targeted the same tower I attacked; after that I was mostly too far ahead to notice what the zeppelin was doing).
For the zeppelin escort, my first attempt was using a less than optimal strategy. The glitchy Target Lock (that doesn't necessarily lock) and target selection didn't help, either. If I'm pointed directly at a nest, in range, and hit the right stick, why the heck would the game target a flying demon way above me, or off to the side, and not at least cycle around to the nest? Anyway, the zeppelin made it to the point the captain decided to change the plan [spoiler] and kamikaze, but Zandalor barely finished saying there must be another way when it was destroyed.

I reloaded my save at the start of the escort, and attempted to be more systematic clearing the nests and towers. When available I tried to use the Wrath of the Patriarch on the densest cluster that was relatively close, and then flew around taking out individual structures and smaller groups, and also summoned a wyvern whenever I had a moment and thought of it (which wasn't often), figuring an extra target might help the zeppelin. I started off doing much better, but when Zandalor told me to redouble my efforts I noticed the zeppelin's health had dropped a fair bit. Looking back, I discovered it was mostly passed a platform that I had missed clearing 4 or 5 ballistas from. Rather than try getting to the end I reloaded a save from a few minutes previous, and made sure I didn't miss anything the next time. Somewhere after the mid point but before the final section I went up to level 47. The zeppelin's health started getting a little low towards the end, but they made it
to the fiery death they were destined for.
[/spoiler]

Flames of Vengeance Zeppelin Escort

Zeppelin Problems

Zeppelin Escort


Here is a YouTube video of the escort mission, which may help you get an idea of what to do.