Couple things I notice - and please, I'm just trying to help so if you know some of this stuff, my apologies - it just doesn't seem like it from the way you worded your post...
First, you can't breed a dumerils to a BCI. Dumerils are a different type of boa altogether - it isn't a 'color', it's a species.
The Dumerils are the only one that will fit your criteria of around 6ft. Your columbian RTB is a BCI and will reach around 7-9 feet if its a male and around 8-10 as a female. They do generally have good temperaments though.
I would do one of two things. First, have your current Dumerils sexed and get one or two more to make a pair or trio and go with that since they fullfill all your criteria. Dumerils may not be quite as marketable though. They are often an 'overlooked' snake. I personally love them, but they are overlooked by many folks. There also are not currently any morphs available in Dumerils. I believe there are one or two out there, but not yet available to the general public.
Second, have your current hypo red tail sexed and get an albino to pair with it along with another morph of your choice. Hypos and albinos are key ingredients to making sunglows. It seems as though many of the BCI morphs are fairly marketable. But remember they will grow bigger.
Hope this helps!![]()