Nah, I wouldn't put any more weight on that animal. Relatively few boas ever really ~need~ rabbits but if you go that route keep them on the smaller side and only maybe once a month/6 weeks.
I've also seen much bigger boas. BUT, the biggest boas are the oldest boas. At 5-7yrs old she's just become a mature adult. These animals should hit 20yrs old without breaking a sweat but they only get that age with mindful husbandry practices. Not a race for them to get huge and some just won't get huge ever. Just like people. Doesn't matter how much you feed me, I'm not getting taller than 5'4" in my mid 30s now. There are genetic size maximums for all species, doesn't mean they can or will ever reach them.