Still a little concerned (and it was my only concern lol) about the substrate, but like a lot of ppl pointed out, there are definitely more cons than pros in feeding in a separate tub, and further research rly consolidated the fact of how counter-productive it seems. My original intent was to feed him in his tank, anyway, but now I'm 100% sure, and am going to offer him his f/t into his tank.
Again, thank you so much, everyone who contributed to this topic. <3