Of course you could. You can refit as you please from any American Naval base, tender, or your home base.
American bases got the Upright anchor
American tenders got the Upright anchor too, but you find the anchor on water instead of dry land.
Your homebase is the only one you can refit and/or end mission. Has a tilted anchor.
If you want to skip the 2.5 thousand km trip to Midway and start from Midway, load this mod
http://www.subsim.com/radioroom/down...o=file&id=1270
Cheers.