Modern welders use internal logic to control voltage output -- and a whole slew of tricks in between. A 7% voltage dip will mean nothing to it.
Small fan motors won't notice voltage drops, either.
Modern lights use the same voltage insensitive tricks that the welder uses. They won't be affected at all by 7%.
The only load that would object might be the air compressor. You have omitted any statistics for it. Some units, pitched as 2hp are actually 1/2hp as NEMA would define it.
Lastly, your calculations assume that all of the loads are pulling full -- and at the same time. For the bulk of the time, voltage drop for this set-up will stay way below 3%. No-one welds all of the time!
The air compressor is an intermittent load, for sure.
