I would be really leery of doing it that way ,to mix up large quantities of epoxy cabosil and have any working time you will have to use a very slow or tropical hardener.You are talking about mixing a very large quantity of very dense adhesive here,then getting it into the tubes and dispensing it,what happens is you get small sections in it where hot spots form and kick off ,this usually is not a problem but if that happens when putting the hull halves back together you will get hardened sections causing gaps in the glued surfaces.
I have done the way you are talking about before ,total PITA,I would think at the most two tubes of this would do the trick on a top deck conversion,this is one those steps where you really don't want to cheap out and maybe not get a proper bond.The working pot life on this product is 42 minutes,plenty of time to dispense it ,clamp it and get everything just perfect,no hassle ,no guesswork,for me thats worth quite a lot.
I am offering you same very sage advice from someone who works with these materials on a regular basis,do with it what you will .The last time I glued a hull together I used a fiberfilled epoxy I found on Ebay,it was already in a very heavy ,sag free state when mixed and was used to glue satellites together .
I loaded it into cardboard tubes and applied it then flipped the hull over and ran a bead down the seam,that product had a seven day cure time and was one of the strongest epoxy glues know to exist at that time.I also used the same product to fill the transom on my 1961 runabout boat.I dug all the old wood out with a chainsaw and filled the cavity with the epoxy,you can literally take a hammer to it and it will not phase it.