SSD lifetime, hibernation, and mobile TM
Since OS X has TRIM support, the wear from writing 8 GB of sleepimage data would be spread out evenly across the drive by the controller in the SSD. Assuming 10,000 write cycles per cell and your estimate of 25% of drive capacity per day, you will be fine for 40,000 days (110 years) if you don't do anything else with the SSD. 

That number could be completely wrong due to write amplification, but if the data is actually being written sequentially it shouldn't be a problem.