Pacman frog and Pixie frog

Question
QUESTION: Hi

I did research on the two frogs I'm still confused about the heating requirement I know they need it between 75 degrees to 80 degrees but how do achieve that?  Would using a heating lamp dry them out and if you would use a undertank heater won't that burn their delicate skin if they burrow deep enough?  

I want to get them both as babies about the size of a quarter my friend told me to get a 5 gallon for the baby pacman for now because they let food come to them as they don't go after the food so having a smaller tank won't give the crickets all that roaming and hiding space and the frog will eat better in a smaller space?  But wouldn't using a heating lamp dry out a smaller tank?  But he did tell me to move it to a 10 or 15 gallon when it gets bigger.

He then told me to use a 10 gallon for a baby pixie as he has two adults now and he told me when he remembered them when they were younger he was able to put the baby pixie in a bigger tank than a pacman because unlike the baby pacman the pixies actually followed the crickets around the tank even though they are ambush predators and he told me when they get bigger get a 20 gallon long for the pixie I could see I probable be able to put a heat lamp on the longer tank since its a larger envirionment but wouldn't a 10 gallon still be small to put a heat light on it?

My friend has a reptile room that has a lot of basking lights for his reptiles so the temperature is about 77 to 80 degrees for his snakes and dragons and the frogs are in the same room so he won't need a light on his frogs.  But my house is room temperature so its cooler 70 degrees to 72 degrees so I figured in my case I would need to do something different with the temperature.

Thank you for your time

ANSWER: Ok, my first question which will help me answer you is how warm is it typically where you want to keep these frogs/toads with that I will be able to accurately answer your question. I apologize for the delay I was on vacation and forgot to change my status here. Once again my apologies.

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QUESTION: The temp is around 72 degrees in the rea I want to keep them at.

Answer
Honestly, the temps are guidelines and not a definitive have to do thing. I think with the temps you have as long as they are eating after a week or so of adjustment period they would be just fine. if not I would use an under tank heater on a thermostat to make sure that the heater keeps it constant and I wouldn't worry too much about them burning themselves.