I always find it a bit distressing when people get information that 10 foot long BC's are somehow the norm. The big BC's are the exception, not the rule and that includes BCC. If you are looking at a 10 foot long BCC/BCI, odds are it's a female, although "some" males can get there, but the fact is big snakes are OLD snakes. You should not be seeing 10 foot long specimens on a daily basis.
If so, those snakes are likely to die an early death because of poor feeding practices.
I base my statements here from reading material written and posted by Gus Rentfro, and Vincent Russo who are world authorities on boa constrictors.
So, to answer you question; "Are there any boa species that stay under 10 feet?" Almost all of them do.
Again there are exceptions, but you are highly unlikely to end up with a 10 foot long boa constrictor especially if you get a male BCI. BCI includes the island or "dwarf" locals, and the Colombian BCI west of the Andes.
If you really want another BC, feel comfortable in getting any BCI male, and just about any type of female. If somehow it ends up 10 feet long 10-15 years from now, you raised it well.![]()