Well - change battery at lunch time
if battery dies before lunch it is f*cked or a low capacity one and you spraying and praying too much
most of us use 1 lipo in morning, change battery lunchtime - job done
if you think about it, say you put on a crane stock...
you still gotta take out the old battery, open crane stock, swap them over, replace old battery in crane and close it all back up again on the field etc......
your battery should last until lunch - if not it is probably a dying nimah 8.4v or something
so in that case you don't need new stock but new batteries - lipo perhaps one day