I’ve done a lot of Blood raider grinding, but I can’t grind for faction standing.
I’m assumming you want + standing to be defended by their fleet, but here is my advice:
Use Suitonia’s method using the glamourex booster to mass decline level 3/4 sec missions. Take RECON and Cargo Delivery. You can do recon 3 in a speed boosted interceptor.
For standings, if you can’t do level 4’s you are better off grinding level 3’s because the faction boost is so good.
You will need SOCIAL V to be able to decline without a standing hit with the booster.