telestix; good for you. You should be able to park overnight in Lot 1. As long as you don't enter the CRA when its operations are shut down for the night, I guess.
The issue of parking in both Cypress Prov Park and Mt Seymour Park has been an ongoing one.
The Friends of Cypress Prov Park have been very active trying to resolve it.
For more info:
https://forums.clubtread.com/8-britis...ewsletter.html paragraph 3.

http://www.env.gov.bc.ca/bcparks/exp...gs/mt_seymour/

http://www.mountseymour.com/winter-parking-designations