He still has a little bit of tail left so that might be a reason he isn't eating much.
They absorb their tails and until it is all gone they might not eat too much.
If you have the same type as I do the top is metal screen, I wouldn't worry too much about melting it.
if it is not metal then you might have a problem..
The Zoo med mini doesn't put out much heat it was made to be safe to apply on plastic critter keepers.
so it won't get too hot.
I have a zoo med medium on my EXO terra 20X20X18 L X W X H
and with the 75W ceramic heat emitter in a mini deep dome fixture it keeps it right at the 80F when my house is at 66F
I also have plexi glass covering the area where the CFL hood lamp is and a few smaller pieces overlapping on the front part
where the ceramic heater is so I can have as much of the top covered as possible with out the heat emitter melting the plexi.
I am sure that when you get your enclosure and temps and humidity sorted your frog will be fine.
New owners tend to panic a bit, I know I did.
Just keep offering food and when he is ready, he will eat.
BTW the little one looks good. Love the colors.