Just had a look at one of this guys books - other things he takes on a long ride,
carob cashew bars: cashew butter (1 cup), 3 tbsp honey, 1.5 cup protine power, 1 cup oats and 1 tbsp caob powder - mixed and refridgerated then cut up and tin foiled for the bento box.
chocolate almond butter rollies: 1 tblsp almond butter, 1 teaspon honey, 2 tblspn carob chips into a wrap (maybe you can get a yeast free one?) - rolled up and chopped into bite sized pieces.
This guy still take electorlyte drinks and gels on a long distance race though.
Have you heard of the 'GAPS' diet - stands for Gut and Psychology Syndrome Diet - I don't know much about it but have heard bloggers rave about it as a means to a healthier gut when in trouble with GI issues like yours. Might be worth a google.