[F150 Man 4Eva]

I was just wondering today, when I haul a substantial load (like my boat or something) if I running my tow tune..should I ever have to mess with O/D? I actually rarely ever turn off my over drive, but I was just curious. Seems like with the programmer, I should really never have to mess with it. Also, seems like I read some where that you do not want to haul anything while running the Perf. tune. Is this true, and if so how much is to much to haul while running Perf.? Say I have a ton in the bed, is that too much?