Not seen the trunks/crop top combo since Dave Scott and Mark Allen in the IronWar era.
However, if that's your thing, then maybe you should get yourself along to this gym session, as you'll benefit from some strength/core/conditioning work, and it's good to get away from the three disciplines occasionally:
If you really want to carb load, then you need nothing more than something like pasta or rice, and a bit of chicken, the night before. Keep it plain too (i.e. no creamy sauces or owt funny like prawns) so as to avoid getting a dicky tummy on the day of your run.