Phil, I certainly wouldn't run without the inner hub seal, and i wouldn't take a chance on leaving the outer hub seal out. That to me is my second line of defence. It is there to keep the diff oil from mixing with the grease in the wheel bearings. The oil can walk along the axles. It doesn't have to be used at steep angles to get oil to the hubs.
The idea is to fully pack the wheel bearings, but not to pack the hub cavity.
I always work the grease in from the big end of the rollers until is comes through at the small end (of each cone)
I give the hub inner a generous wipe of grease all over the steel surface,(this is practicing paranoia
) but leave the cavity otherwise empty. ( the cups and seal track get coated as well, of course)
Back around WWII and earlier the grease was not as we know it today.(I think Moly was a WWII discovery) It used to melt and run like oil in the hub and the procedure was to partly fill the hub. The grease melted and ran into the bearings) (using the old grease without your inner hub seal (BB-1175-c) would have filled your brakes with grease on the first run)
Nowadays the grease is so much better that some car wheel bearings come factory packed and when they deteriorate they are renewed.
The high melting point moly (molybdenum di sulphide) greases don't melt. It requires only a small quantity to adequately lube the bearings. (the rolling action never completely rolls the lube away)
When I was an apprentice, (early 70s) front wheel bearings in a car were generally re packed annually or at about 12,000 miles (20,000 km) Today I would think many factory sealed (factory preloaded) wheel bearings are good for a million km.