Trying to test some integrations using TBA against a release preview. Struggling to the the REST API to work. Any tips? My (fake) accountid is

TSTDRV1234567

So my new URL for the release preview is tstdrv1234567-rp.app.netsuite.com I think the AccountId I should use in the realm for the TBA signing is

TSTDRV1234567_RP

and the URL is https://tstdrv1234567-rp.suitetalk.api.netsuite.com/services/rest/record/v1/ but it doesn't seem to be working. I had to create a new token in the RP account, as those didn't come over, so I'm using the new token. Any tips?