Simple rule for tri nutrition - lots of it!
I reckon on choc soya milk after a hard session, toast & marmite (for salt) when it's hot, but otherwise wouldn't particularly bother too much about fiddling round with percentages of this & grammes of that. Just try to avoid actually eating the table as well & you'll be right.
I'd suspect your bodybuilder friend was talking about bodybuilders. You don't want to end up looking or training like a bodybuilder, so you probably need to look more at carbs. Flapjack is good, so is malt loaf & jam sandwiches - see what suits you.
BTW, I'm vegan, have been running maras & long stuff for a few years & did an IM last year, and have never used protein supplements. I'd use proper 'sports drinks' with electrolytes in for long or hot races though.