I do a 50 mile bicycle ride in the tropics on Saturdays. I’ve learned a few things.
If possible, Leave early; just as the sun rises so you only have one way in the direct sun.
There are a ton of sport gels out there, but the most important thing is electrolytes: trust me, the salt, potassium and magnesium will keep you more stable than the carbs in those gels— carbs were something you should have loaded the previous day. It will also optimize your hydration so the water doesn’t just flush you out.
I’ve done LMNT packs which just have stevia and flavoring. Or purchasing Potassium, Magnesium from a place like powder city or bulk supplements ADDING pink sally, and mixing a small dose together to do make my own diy style LMNT. I’ve tried maybe a dozen different gels that contain those with or without carbs and caffeine, but I can say those 3 are really all you need during a run if you’re eating well
Check out f2c electrodurance if you are in the us or Canada. I don't think there is a better option at a better price. Although i think in response to the original question, electrolytes aren't going to do much for you if your muscles aren't properly fueled. I like maple syrup for cost effective running nutrition. Table sugar is probably even better from a cost standpoint.
There's only so much glycogen your muscles can store though, right? You will eventually burn through all of that even with the most heroic carb-loading effort.