If you instantly gut and gill them you might be able to make a few days. Those large boats D speaks of have very large ice holds and instantly gut and gill fish before going in (the better ones anyway). But don't let them sit in any water. Crushed ice is best and packed tightly in and around each fish. Re ice and repack often and keep water off them. What your asking to do is one of the few times I would suggest one of the high end coolers like Yeti or RTIC. Best option might be to filet out the live fish and ziploc bag or vac seal at end of each day then ice down good. That is probably how I would go about it if forced into that position. The guts, gills and blood are what will turn the quickest and spoil them.

