I would go no bigger than a 64mm if you pull a trailer. the bigger you go the worse it will tow is the way I look at it unless you get twins. a 62 should work really well for you

 

I have a htt 64/65/13ss and love it. Towed my bassboat (4k) last night on Smarty TNT level 5 and ran it wide open getting up to speed at times and egts never got abot 1350. So with less fuel, a 62/65/13ss should do you well. Tac

 

I have a 62/65/14 on my 01 and I would go with a 64/65/13ss if I had it to do again.

 

SILVER 62, i just installed one on my truck. All i can say is WOW, smarty on sw9 the highest egt i have seen is 1100*.