I do not have one mounted on the bow, but on my 265 when I run offshore I strap a 6 man life raft in a canister to the bow. I know on many bigger boats, guys have mounted the canisters on the hardtop. I called Grady and they highly advised against doing so on my 265. Not sure what Grady will recommend on a 282, but they will be able to answer your hardtop can support the weight of a canister on top. Grady's reason against mounting on the hardtop was that the extra weight and pounding from waves adds a bit of force on the hardtop mounts and fiberglass itself, where the canister would be mounted is not reinforced for such weight. The canister is not a ton of weight, especially compared to the radar's and other electronics have mounted up top, but I am assuming it has to do with the location.
Most 282 I have seen with canister's usually place them in the walkway at the bow when running offshore. They usually tie it down here, since it can be kept low which will not effect your line of sight when running, is on the bow so hopefully out of your way, and is low so it will not make you roll as much as a canister mounted on a hardtop would. If you are buying new, or can find a newer used valise bag, that may be a better option and less weight on the boat. I got a free canister life raft so I took it without thinking twice, but if I were to buy one, it would be a valise. The valise would be easier to grab and release then cutting straps on a non permanent canister. I have my whole crew carry pocket knives in case the boat flipped or something goes wrong and the canister needs to be cut from the straps and deployed. I don't plan on ever having to deploy it, but you cannot plan that and my crew will always be instructed of what to do. Having a plan can save lives.