Like I said, the Plasma Rifle does a decent job of lowering shields (at close to mid range), but you do have to rambo a bit using the computer console as cover rather than the crates near the door. In the previous room (the first big wave of enemies pouring out of the latched on ship) you need to pick up and drop as many plasma rifles as possible, so they don't despawn -do the same with PP if you are doing it standard.
Once the Zealot comes, PR/BR combo him, or stick him and you can use his energy sword, if you are comfortable going up close, otherwise you may have to expend a bunch of BR ammo to thin the ranks.
The jetpack elite section before the bomb room is a real bitch, mostly because you have to make sure to save a PR from the lift and it's way shittier at dealing with them. The bomb room is just awful. Have to spam grenades, pray they don't dodge them all and then get up close and personal.
If was a Vidmaster I'd be ready, but I wouldn't recommend it...PP is best Legendary weapon. Except for with Brutes, then it's Carbine all day, maybe Beam Rifle.
Yeah I like to impose painful challenges on myself. Having said that, I can't stand SLASO, maybe just because it was Halo 3's campaign, but I just found it boring having to put 2 PP shots and a million bullets into one enemy. I might try it on Halo 2, because I actually like the campaign, and know it on Legendary like Cosmo knows OoT, but I feel like it would be awful. Also if 'all skulls' contained Bandana that would kind of defeat the purpose of the run.