When I entered BMT my weight is also around 45+kg at 170+cm, and
I went through the 24km route march successfully.
About the field pack getting lighter, I think it's true. The
first time I carried my full field pack, I thought I'm going to
sink into the concrete ground. I could hardly walk around, let
alone believe I can survive a route march. But as the weeks go by,
the field pack somehow feels lighter and lighter, to the extent one
could even do pull-up with it on.
So ya, there's no reason why light-weight personnel can't
survive BMT.
And I agree the water parade is a joke. Yes, adequate hydration
is very very important, but to drink one litres at one go, isn't
that outright torture? I never understand why they can't allow
soldiers to lesser each time but have more water parade.
Water parade is like...less than 2 minutes? Conduct more water
parade (but drink lesser amount each time) can waste how much
time?