I don't use commercial gutloads, but my dubias are always fed as though I were about to feed them off. I only have one gecko that eats them regularly (my tokay Erzebet) so I tend to have a ton of roaches and sometimes have to give them away or sell them, but they're so cheap and easy to keep it's no big deal.
I don't ever mist or water mine. I experimented with that in the early years and found that it almost always led to mold growth. I use a minimal amount of ventilation holes and feed green stuff about twice a week.
it takes them about 2 days to eat the green stuff, which contributes to humidity. so the humidity will be a little up, then I let it "dry" for a day or so before adding more green stuff. this works in my colony, where I live, with the relative humidity in my herp room. it's a bit dependent on time of year (when the heat's on in the winter things dry out faster, etc) so I have to sort of pay attention and adjust.
I suspect you'll also have to try a few things before you get the appropriate balance. I also, when adding greens, rigged some wire in an upper corner of the bin and hang the greens from a clothes-pin. greens in a dish or laid over the egg crate get icky and contribute to mold and bacteria, at least for me. it's a great way to suspend pretty much everything except things like fruit/veggie peels or small bits of stuff. I usually use dandelions, beet greens, collards, carrot tops, just a random variety of things from my kitchen, but I keep it low in fruit (no citrus at all) and don't use most types of "lettuce".
for the protein/fat source, I use a dry mix I make myself and it varies in composition, but is always dusted with calcium and usually contains a small percentage of repashy diet.
these dubias are ~95% of my tokay's diet. she has been eating this for about a year and a half, since she was tiny. she is well-grown and has good bone and body structure, so although this is very non-scientific I feel pretty good about it. I use the same general ingredients you see recommended frequently by experienced herpers, just the composition is variable over time and I do NOT use dog or cat food, or anything high in protein like fish flakes or meal.
edit: and this time of year, ~once a month I'll give them a corn cob. it's like a treat for the roaches, probably because of the fat and sugar.
