First, make sure kiddo still fits the seat by height -- there must be at least 1" between top of head & edge of shell/frame. If there is less than 1" then the seat is no longer safe for baby to ride in the car with & I suggest a Cosco Scenera or Safety 1st Uptown (Uptown has EPS foam like in bike helmets, Scenera is very inexpensive & both are lightweight for travel)
The Snugride manual does allow this carseat to be installed without the base, but it's generally more difficult & time consuming to uninstall/reinstall frequently, which also increases the risk of misuse & injuries associated with misuse. I personally would pack the base JIC. Do you still have your carseat manual? If kiddo still fits the Snugride & you've misplaced your manual you should request a replacement copy immediately.... Make sure that you're also following the vehicle manual!