The beetles should be fine, a few times on accident when getting mealworms out for my beardies they've ate a few beetles, the two adults I have don't really like them but my younger one seems to really like them oddly.
How old is your bearded dragon currently? Generally you do not want to give mealworms to a beardie unless they are 6 months of age, and superworms can be given at about 12 months of age. Also be careful for bites, mealworms may not do much to an older dragon but superworms could potentially eat your dragon alive while it sleeps, same with crickets.
Also be very careful with bioactive tanks. Personally I would only do a tank thats about 6x2x4, but I've seen some people do tanks that are 4x2x4 and seem to work well as they still offer tons of options, tons of climbing space, different heat levels and different UVB levels.
Also the reason that 6 feet of length to me is necessary is because this means you have more space and can provide more options, thus lessening the risks a tiny bit.
If I were to have a 6x2x4 enclosure and make it bioactive i would have about 3 feet of space thats mostly a rocky and clay area thats dry, and then another 3 feet of space would be where the particle substrate is. I'd also have tons of ledges, logs, branches, and hammocks to make sure my bearded dragon could use the upper space of the tank and get off of the bacteria infested ground as well.
And of course provide multiple basking spots and UVB levels to make sure that the bearded dragon could have a variety of temperature and UVB levels.