Flying blind is difficult but not impossible short term. You might want to check your local pool store to see if they sell replacement testing supplies. Call around before heading out. Your looking for the Taylor FAS-DPD Titrating Reagent (Chlorine) R-0871. Just don't let them sell you anything else

You said you got an 80 CYA reading correct? Was that with or without diluting the pool water sample with distilled water? What last two FC readings did you last have (before running out of reagent) and how far apart time wise?

For your size pool, adding 1 jug (121 oz) 8.25 % bleach should add 3.5 FC. You can guess how much you'll need by the amount of FC loss you had over the last two readings. Not perfect, but will keep you in the game.