I mean don't get me wrong you can try a f/t hopper but what if he doesn't eat then he may not want to eat when you offer him live. I'm just pointing out what I would do to get him a little weight on. A small live hopper would be the best bet especially if he's not already eating f/t. Then the feeding after I would try back with f/t. For me if a snake is under 100 grams I don't like them to miss two meals. While some can and some can't depending on how much under 100g, this is more or less my comfort zone.