Here's the best I can find[1]. It very much depends on the state, but that constitutional analysis says that it's possible the relaxed search rules could even apply to individual hunters or fishers. I can't find any definitive court rulings either way on specifically searching a freezer inside a house, but in other cases the courts have generally been deferential to the state's interest in protecting its wildlife. Plenty of hunters have experienced such searches, so it's a real problem.

Why then have these interior searches never been challenged? One reason might be that these abuses virtually exclusively affect low income suburban and rural white men. They don't have the resources to take a case to the SCOTUS. The prestige media is uninterested in advocating for them and the ACLU and other pro bono law firms don't prioritize that demographic either. Given the choice of paying hundreds of thousands of dollars out of pocket to litigate or pleading to a misdemeanor and paying a $1,000 fine, so far everyone has chosen the latter.

[1] https://repository.uchastings.edu/cgi/viewcontent.cgi?articl....