It isn't the CFM that matters but rather the maximum static pressure that can be developed by your DC. Odds are such a small DC probably won't collapse the average can (metal or heavy plastic), but it's impossible to say without a bit of real-life testing -- and with metal cans you only get one try because the can is useless if it is collapsed. The worst case scenario is with all your blast gates closed (or the inlet *fully* blocked), so that is what you should test with.
If your fiber barrel is made of 1/8" fiberboard (or heavier) and has at least some reinforcement around the top rim (such as a metal lip) then it is very unlikely to be collapsed by any practical hobbyist DC under 5HP. However, a fiber drum is going to be one of your heaviest alternatives and you'll likely have to add handles to it as they can be awkward to carry by themselves when full of sawdust.
That said, reinforcing a trashcan isn't all that much trouble, really. With my health, if I can do it in a few hours, plus add 4 windows, then I would imagine the average (healthy) individual could probably do it in a half-hour or thereabouts. All you need is the aluminum bar, a drill with 1/8" twist bit (for rivets), a marker, a ruler (or other measuring device) and anything that can be used to cut the aluminum bar to length (for which you can use your tablesaw if you have nothing else). Then add to that the 1/8"x1/4" aluminum pop rivets (and 1/8" backup washers *if* adding Lexan windows) plus any sort of riveter -- you can use screws but rivets offer a lot in this regard and leave no sharp protrusions in the trashcan when finished. A piece of paper, or a calculator, can also come in handy for the very limited math (i.e. diameter x 3.142, plus a few inches for overlap).
If you don't already have rivets and a riveter (the only "atypical" shop items above) then you'll be surprised how handy a tool a riveter can be when it comes to household repairs and for fastening sheet metal to sheet metal or sheet-metal to plastic.
