[pct-l] feet larger in desert?

[Julie Guibord]

I'm planning to start the PCT mid-May at Campo (due to a must-attend
graduation).  I've read  many suggestions to start with trail runners a full
size larger than I'd usually wear.  I have some questions about this.
First:  In normal life I like my shoes (running shoes) with 1/2 inch space
between the end of my big toe and the end of the shoe inside.  Second, I'm
58 years old and I've had four children.  My feet went from a size 8 1/2,
before children, to a size 10 after the last child. That was over 20 years
ago.  These days, I'm still a size 10. Third, I've just returned from a
training hike in FL, four consecutive 20 mile days where my feet did not get
bigger.  (It was cold in FL, and my feet remained wet for 2 1/2 days through
swamp crossings.)  Any opinions about whether my feet will REALLY get a full
size larger?  How much extra length should I allow?  I plan to wear
mid-weight wool socks.  Also, if my feet get larger, will they remain so for
the duration of the PCT, or is it just a desert phenomenon?

Thanks,
Julie