Luke....yea, that inexpensive camping bladder actually works out really well once I figured out suitable fittings, and feeds instantly to the sink pump/faucet (surprised me) in terms of functionality. Bonus IMO is just stick a dock hose thru the bow hatch to refill, no need to haul in/out to refill. Bought 2 of those so have a backup/spare for another 5 gal on the ready, just swap the modified cap out and done.
I did price some various v-berth bladders (fresh water containers) from several sources to fit that space, mighty pricey, and for our use, 5-10 gal per outing is way more than enough (our h2o useage is minimal, supplemented with spirits or beer)!
Cheers, get you boat wet!