Note that you will need to build up that new account to level 16 (i believe) to unlock the seasonal event used for
GTP_Registry Qualifier, but that takes about 30 minutes.
Just share a car (e.g. 2J) from your main account and borrow it with the new account and run a few seasonal events and destroy the AI with little effort.
A few seasonal races will get you to level 16 and will also give you enough credits to buy the cars used for competitions for a few weeks. A good percent of weeks the WRS uses arcade cars which require no credits anyway so the competitions won't require much if any grinding. Just run a seasonal event now and then or run the seasonal time trials when they come out with the new account.