My two cents...I use the water hardening method but I do it a little different than what has been mentioned.
Always keep a ladies stocking in your river gear. Put the fresh eggs in the stocking and tie it to your pants so it hangs in the cold river. Continue fishing. After 15-20 minutes put them in a Ziploc
TA DA, cured eggs. Freeze em if you want or use em.
Tip of the week...Use new stockings, not your wife's old ones with holes in them