trip: note park entrance pass plan

TODO.md

@@ -10,6 +10,10 @@ Open items before and during the trip. Tick and date when done.
   Sequoia/Kings Canyon and waives the US$100/person nonresident surcharge.
   Without it: ~US$435 per park, US$870 total. Pass holder must be in the
   car with photo ID at every gate.
+- [ ] **Print the pass PDF** after purchase and carry the physical copy.
+  The planned Big Oak Flat and Big Stump entries are daytime fee stations,
+  but an unstaffed entrance requires a physical pass or printed PDF to be
+  displayed. Ask the ranger for a physical pass at the first staffed entry.
 - [ ] **KT: complete the LA DTLA online check-in form** —
   [Hostaway portal](https://guest-portal.hostaway.com/65596088/dxYlP4ov/check-in).
   Entry code is activated only after it's submitted.