That is going to make the fish in cycle a bit trickier. Normally you would test daily and do water changes as indicated by the color on the test. But that isn't much of an option. That changes things. I've seen digital pH meters and such, but I've never heard of a digital ammonia or nitrite probe... Besides, I don't know about their accuracy, but I do know that they are ridiculously expensive.
Since you won't really know what your water tests out to be on a day to day basis, I would recommend doing daily 75% water changes just to be safe and keep your feeding on a minimal level... every other day or less. Keep a log of your water changes, feeding and test results from the LFS. This will help you find patterns in behaviors and testing results.