I think you've got a perfectly good point, although there is a rather
nasty dip in the Van Allen zone of death that needs to be avoided like
the plaque. With the magnetosphere of mother Earth failing like no time
ever recorded, chances are that the Van Allen dip has become a rather
large no-fly zone.

Perhaps sending up a few relatively small SBRs offers the most reboost
bang for the almighty buck/euro, as well as achieving best percentage
of delivered energy per launch tonnage. Although, a few extra tonnes of
regular rocket fuel and if need be a spare engine or two is perhaps
their best option.

Regards, Brad GUTH / GASA~IEIS
http://guthvenus.tripod.com/lunar-space-elevator.htm