So the credits/xp rewards have changed for the remote races. Less credits, more XP.
I ran a 20 minute Daytona race, and here are the credit rewards for the finishing positions:
1: 20,200
2: 15,150
3: 11,110
4: 8,080
5: 7,680
6: 7,270
7: 6,870
8: 6,460
9: 6,060
10: 5,660
11: 5,250
12: 4,850
13: 4,440
14: 4,040
15: 3,640
16: 3,230
For every 100,000 credits, you get about 180,000 XP, I think. So almost double compared to credits.
In theory, if all your 6 bobs finish in the top 6 constantly, and they race 3 long races per hour, you can make 69,490 x 3 = 208,470 per hour.
And in theory, if you have 4 accounts, so you can run 16 of your own bobs in all the races, you can make 119,990 x 3 = 359,970 per hour.
And if you run the races automatically through the night, in 12 hours you could make 12 x 208,470 = 2,501,640 (6 bobs), or 12 x 359,970 = 4,319,640 (16 bobs).
In reality, however, you can probably get one long race done per 25 minutes (including loading times, and some races take longer), so in 12 hours you'll likely get about 28 races done.
That would total to 1,945,720 (between 6 bobs), or 3,359,720 (between 16 bobs).