the biggest difference between 50 and 41qt tubs is the width. There are actually 2 different lengths on 41qt tubs. Some are 29" long and 17" wide and others are 34" long and 14" wide. I use a 29" long 41qt for my 1900 gram female, and she does perfectly fine with it. Fed her for the first time last week, and she had no hesitation at all. I think that the 50qt would be fine. As long as he is eating that's what matters right? Plus it will be a lot easier for you to keep the humidity up.

Good luck =)