IMO, rack systems for larger snakes are over crowded. They work great for the hatchlings/yearlings even sub adults but a 8' snake in a tub...??? Using a basic ruloe of thunmb of 1 square foot of floor per foot of snake equals a 4' x 2' minimum for a 8' snake. That's some pretty large tubs. I've seen pics of freedom breeder racks that have quite large tubs that should be large enough for adult boas.
For my collection I prefer having various sized cages for the various sized adults. Last year I bought a couple of stacks of Boaphile cages. Seem to work pretty good. I have the 4' x 2' x 11.5" ones now and am planning on getting one more stack of 6' x 2' x 17.5" ones for breeding cages.
Bottom line is all caging and/or racks have advantages and disadvantages. Do what you're doing, look into the possible solutions and decide what will work best for you.
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Thanks,
Dave "Rainbows-R-Us"
0.1 Wife
0.2 kids
4.12 Brazilian Rainbow Boa
1.0 Hypomelanistic BRB
0.1 Het for Hypomelanistic BRB
0.1 BCI "Elvira" normal from 1989
1.0 BCI albino / het-anery
0.1 BCI Hypo / het-albino
0.1 BCI Anery / het-albino
0.1 BCI Hypo (possible super)
1.0 BCI albino het stripe
1.0 BCI salmon hypo
0.1 BCI ghost
lots.lots.lots feeder mice and rats 