Yes, there are creeping Ceanothus. Most commonly sold are probably C. gloriosus, C. 'Joyce Coulter', and various griseus selections. if you are truly in a Zone 6 situation none of these low growing selections will likely winter over. Moving your newly planted specimen would probably best be done in the fall.

What part of WA?

I'm in zone 8, no idea why it was set at zone 6 (operator error!)...I'm on the Olympic Peninsula west of Port Angeles...and this ceanothus has settled in and wintered over well where it is located. Too bad I didn't realize it was a creeper!

C, gloriosus is the most likely. It is quite low and has been much offered here. Other species as prostrate as this one are not seen in general commerce, being more fussy about site conditions. Unfortunately, like most other ceanothus important in gardens C. gloriosus has a fairly high minimum temperature and is liable to eventually freeze out at this latitude. Those occasional winters when it falls near to or into the single digits F. - like it did north of Everett last winter - are murder on numerous trees, shrubs and other plants that would otherwise survive here indefinitely.

Port Angeles near the downtown at least shows signs of being a mild spot - your site may be able to keep the ceanothus for a pretty long time, maybe as long as you will be gardening there. It all depends on your individual site conditions.

A bamboo enthusiast I once visited who lived not far back up from the beach, in the very start of the hills had had 28F just before I was there - due to the effects of cold stale air streaming down from the coastal mountains. This was in southernmost coastal California.