12-15% has been the sweet spot in my experience.How much would you say I need?
The absolutely MAX at the limit would be about 1000lbs of tongue weight if I didn't want any buffers.
10% = 10,000lbs
15% = 6,666lbs
That's on the max side. If I wanted to be conservative and build in a 10-15% buffer that would be 5,666lb which seems too conservative, doesn't it?