If you use alts and swap the gold with genuine traders who aren’t involved in RWT, it can help move the gold more safely. There are plenty of ways to launder gold securely if the gold seller isn’t being actively monitored. However, you will be paying more for security when keeping the gold.
First, trade the gold to a seller alt—level it up a bit and buy membership with a bond or something similar. Purchase bonds on the alt; this will tax the gold you bought, but it’s still cheaper than buying bonds directly. Next, use another alt (not a level 3) on a different IP address. You could even trade or take intentional losses on flips to make the gold movement appear more legitimate.
Then, buy an item and transfer the gold to your second alt, purchase bonds, and repeat the process to your main account. This method integrates the gold flow with real player transactions, and since buying bonds with gold benefits Jagex, they may be less likely to target you out of self-interest.
Also wait around 2-3 weeks before each large transaction to each of your accounts to ensure a rwt ban doesn't hit on your main.