With all the money you're looking at spending for HOBs and/or canister filters, why not drill and use a sump? You could get a fancy low profile kit for like $150, or just go bulkhead into a solid lift, which would be much cheaper. Toss an intake sponge on the bottom of the pvc pipe, now you have a sponge filter. Grab a 40 breeder and either pick up a sump kit, or go diy. You can buy glass/plastic dividers, or just do the walmart multi drawer thing. With that you can do wet/dry, or fully submerge the media. And you'll have a lot more room for media.
Also, if you are uncomfortable with the idea of drilling the tank, you can go overhead sump. Just not normally as aesthetically pleasing.
Also, if you are uncomfortable with the idea of drilling the tank, you can go overhead sump. Just not normally as aesthetically pleasing.