I'm sorry that happened to you. I'm surprised that you were already off to fight Bonemass but hadn't built a Longboat yet. Did you unlock it? You need to craft iron nails and then it will unlock for you.

I understand going naked to pick up your gear--I've done it myself on occasions when it was possible. I only went to dangerous places that way if my partner was watching my grave to give me backup when I arrive. I also always ate the best food I could and waited for my rested buff before taking off to retrieve my gear.

Otherwise I always use my next-best armour, a reliable melee weapon and shield, and my best available bow. Sometimes it's just worth it to make a second visit to the grave to collect any remaining items that were in your inventory.

While your adventure sounds quite thrilling and harrowing indeed, it reads very much like you were woefully ill prepared to face Bonemass. Perhaps you were simply planning to use the swamp he was located in to gather the iron you need, and to find the turnip seeds and Draugr entrails to cook better foods... but that doesn't make sense to me either, because you would've had to learn the location of Bonemass from a stone found in the swamps. Those aspects are intriguing to me.