Since my anxiety on Trazodone seems to happen after being on it for several days in a row, are there any issues if I just took it on an occasional night here or there?
Nope. Even with daily dosing for a week the short half-life means plasma levels at 50mg/day will drop to almost nothing in under 24 hours for most people, so each night starts with effectively a clean slate anyway. This is one reason why I wonder about the onset of anxiety after you've been on it for several days. It would only make sense if you are a very slow metabolizer, and even then I still don't understand why it would have that effect. If you are a slow metabolizer then you will still be sedated well into the morning.
At 50mg/day serotonergic activity never reaches levels that may drive anxiety. It could at 75mg/day, but only for 4-6 hours maximum, therefore it should still all be over by the next morning.