So to answer a few questions.
1) Yes there have been a few times where the tires were run over 65 mph for roughly 200 miles. This was before I knew (from this forum) that trailer tires had a maximum speed rating.
2) I don't recall ever driving the rig over a curb but it's always possible even though I try to avoid it at all costs.
3) The tires have been covered for approximately half their life.
However.....Looks like the consensus is to replace now. I was leaning towards replacing sooner than later but I agree with other posts. I'm going to be pretty far away from home, while not on "vacation" the trip could suffer a significant setback with a blowout.
Thanks for your input, you simply confirmed what I already knew.