I had a trail marathon last weekend and this is the "gu" I made. It worked well. I also eat dates on my runs. I love them.
Bake a sweet potatoe or how many you need.
Mash it up with coconut butter (if you don't have that you can use cocnut oil)
mash in banana, chia seeds, cinnamon and a dash of salt. Add water if you need.
Put all of this in to a squeeze tube (you can get them at REI) or double up on a freezer ziplock bag.
I'm 2 weeks into my Whole 30 (vegan) and it's going great. Can't wait for next weekends race!