Eventually I tried to think outside the box, using Transmogrify into Bat scrolls, and that entropy spell that homes in on enemies. But these tactics are either implicitly or explicitly forbidden by the game. If I missed any obvious highly-useful tactics, please let me know.
Nah, all the easy mode methods were turned off for this mission. It's meant to be a difficult combat exercise. That said, you're correct, the new espers make it incredibly painful. Not that lightning and water were MUCH easier. However, you neglected shields, which can help if you've got decent reaction times.
I came up with a few ideas to make the mission more fair, and I think that even just one of them would have a great impact, but maybe other people have their own ideas.
Hm, these are decent ideas, I'll offer my personal opinions one by one.
-Alter which enemies are allowed to spawn in such a mission (at least removing ice and explosive espers)
I'm not sure this would be necessary, however, limiting their range to 'need to be on-screen before shooting' would be helpful during this mission. I too am widescreen and you're right, that can be very frustrating.
-Add some mechanic that allows players to look farther below the screen (like holding the down key for a few seconds, as in lots of old platformers)
I'd like this mechanic regardless of JtP missions or not. Up/Down would be just as nice as left/right, which already exists.
-Reduce enemies' awareness of the player, as in the stealth assassination missions
This is actually covered by a body enchant you can choose to use. Due to the duplicative nature and the implied cost of switching (which is your light source, usually) this seems like a poor choice of option.
-Make it so that the player can touch certain enemies without failing the mission
With the volume of espers currently, that might be a bit much. Particularly since one of the problems is them shooting you.
Slow drops are my usual method of dealing with 'falling onto enemies'. Not that it helps all the time.
-Make enemies' accuracy with projectiles less than perfect, at least in this scenario
Now this has some merit. With the general idea that at shorter ranges their accuracy vs. your hitbox won't have much of a difference but when they're sniping you it might actually give you warning they're there. I'm not sure just how Imperial Stormtrooper you'd have to make them though to make it effective enough.
-Somehow alter the land-generation mechanics so that players don't have to frequently take blind leaps off of high ledges
Considering this is the 'combat' quest, and Lava Escape is the platforming one, that makes some sense to me. Make it more gauntlet then standard world generation.
-Allow the player to get hit more than once before failing the mission (perhaps 3 times or so)
That seems anti-thetical to the purpose of the mission... a Journey to Perfection.
I'd have to say I'm against that one. Though I personally wouldn't mind a little give on the falling damage, still... it's against the idea. Oh well.
-Include the map in the upper-left corner of the screen, showing enemies' locations, but not necessarily the location of the goal
In this case I'd do the opposite. Show a map showing the terrain, but not the critters. Since this is the 'perfect combat' mission, you should never know where the enemies are. Considering only bosses show up on the mini-map, this really doesn't make much difference from the normal mini-map since there are no bosses in JtP. I'd have to say I'm against this one as well. Though every now and then I'd like to be able to drop a cherry and see how long it took to hear it go splat, and terrain maps would make sense to me.