Octane additives?

I got caught in the middle of nowhere northern ontario in the middle of the night and had to fill my empty tank with 87 +15% ethanol so I added enough octane booster to get it up to the 91 the 10.5-1 needs . Man it didn't sure didn't run like 91 I ended up dumping the rest in going to about 97 and dropping timing to get it to run until the next open station with real 91 .