On rejecting live crickets, did you leave him alone with the crickets? It's not great to let feeders roam the tank, since sometimes they take a bite out of the frog, but have you tried bowl feeding? Putting crickets in a sturdy, non-tippable bowl about 2'' will keep them trapped. Then give the frog some privacy, maybe leave the crickets in overnight.
Other things- maybe you'd want to cover all sides of the tank with paper since your frog is so stressed.
If you decide to make a portable tank, I suggest a storage container over 20 gal. Taller is better. You'll also need an x-acto knife, mesh, and a hot glue gun.
If you can get anyone at all to care for your frog at home I'd do that. Have you tried bribes?