Blue Painters Tape
To get better adhesion, I went to Ace Hardware, and bought three varieties of blue painter's tape, as PVA is reported to adhere well. So, I taped up, and printed a 1/4 scale octopus, and BAM, strong adhesion. I actually had to pry the print off the bed, as opposed to it simply coming off as it printed.
This gives me confidence that I will be able to use PVA as the support for my NinjaFlex prints, provided I can get the NinjaFlex to adhere nicely to the PVA raft.
PVA, btw, is Poly Vinyl Alcohol, a water-soluble filament. It is reported to be used as the dissolving packet for some dishwasher detergent packets. It dissolves right off the NinjaFlex printed part, eliminating the need for me to trim off the support, and enabling removal of support in hard-to-reach places, such as the inside of a klein bottle. Awesome.
Dual fan assembly
I have found that NinjaFlex prints very nicely when coupled with a cooling fan, and the FlexyDually does not come with fans, nor does the stock fan shroud mount to the carriage. So, I printed a new one!
This shroud is printed from Natural PLA filament, 3mm. Extruded at 180°C, onto a 60° bed, it took 14:30 to print, and came out nicely. I did not use support for this print.