Mm, there's a certain angle that I can strafe-run with that'll sometimes (surprisingly easily) give me the lowest air-time and no-interference to get across to the -16 MU ledge, and a few times the 8 MU ledge. That's why I try to stick to the right of the barons, as the approach is pretty narrow and is easier to run up to.
As for ammo, a little map-checking shows
8 cell charges - 320 cells
8 large cell charges - 800 cells
1 backpack - 40 cells
1160 cells total
8 boxes of shells - 160 shells
2 accessible sergeant corpses - 8 shells
2 SSGs - 16 shells
1 backpack - 8 shells (?)
192 shells total
21 boxes of rockets - 105 rockets
8 individual rockets - 8 rockets
1 RL - 2 rockets
1 backpack - 1 rocket
116 rockets total
And superflous amounts of bullets, minus a little sniping.
For 3 cybers, 2 SMs, 4 arch-viles, and 2 PEs needing plasma/rockets, leaving 160 or so things to kill otherwise. Given 480 cells for cybers, 160 for SMs, 200-240 for the yellow key archs and mancs (others can be taken down with SSG or RL), and 40-80 for the PEs, we have around 1160-920=240 cells, or 6 shots left. A bit of space to move around in, although adding the 4-5 shots for taking cybers down in 5 hits really tightens it up. Otherwise it's mostly SSG, as getting the RL requires getting past a cyb.
In fact it might be a good idea to go; SSG/chaingun, bfg, ignore yk and take RL/plasma gun after killing cyber, THEN get yk and deal. Infighting should probably be about the same both routes considering where stuff teleports in, but would be a heck of a lot more manageable. I think this is how lost heretic managed to get through this map in his FDA.
Well anyway, posting at 5 am is bad, night.