If you are saying that your TW max rating is 800 lbs (that is, you'll never exceed 800 lbs TW), then definitely stick to the 1000 lb unit. I would only go with the 1500 lbs system if you think you'll be going to a larger camper in the near future, and th eBlue Ox company says it's OK with less than 800 lbs TW.
thebrakeman ('70), DW ('71), DD ('99), DD ('01), DD ('05)
2004 Surveyor SV261T (UltraLite Bunkhouse Hybrid)
2006 Mercury Mountaineer V8 AWD Premier
Equal-i-zer WDH (10k), Prodigy Brake Controller