Use your tongue. Kiss his dick instead of sucking. When you do suck him, just go for the head and frenulum; use kissing and your tongue for the rest of the shaft and balls. And feel free to mention that his "HUUUUGE" cock is making you change up the routine a bit because his member exhausts you so much.
Good use of the hands, a nice wet dick, and sucking on just the head will be more than enough to get the job done well.