With tires made in 2004, I would have been willing to bet money that you would have at least 1-2 blowouts over a few thousand miles, especially being that you are traveling in the summer (higher temps). As my signature implies, I had 2 Kumhos blowout at ~3.5 years of age within 100 miles of each other, on both sides. It was on this trip cross-country that I upgraded to 15" wheels. I've also had a 6-year old Marathon blow.
You didn't say what you replaced the tires with, but assuming they are 14" 205 Marathons, and they are less than 1.5-2 years old, you will probably be fine for the rest of your trip. Check the date code in the sidewall of the tire (a 4-digit number).
Unfortunately, loaded TM's really push the envelope on the weight capacity of 14" tires. So once you add other deleterious factors like high heat and tire age, the chance that you have a blowout goes up substantially. That's why several of us have upgraded to 15" wheels (and tires), as they have a higher weight rating, and thus a wider safety margin.
When you pull off the road after riding at speed for an hour or two, touch the hubs. If you can't keep your hand across them for more than a few seconds, you are definitely running on the hot side of normal. That could mean faulty wheel bearings, inadequate grease/lubrication on the bearings, an overweight trailer, and under-inflated tires, among other things.
You say you weighed your TM but didn't say what the weight is. What is it? (both the axle and tongue weight)
Did inspect and repack your wheel bearings before your trip?
What exact tires do you have on there now? What pressure are you running (checked with the tires cold)?
What was the ambient (outside) temp during your blowouts?
Did the blowouts damage the TM? If not, you are very lucky.
My advice: don't turn back home -- you will still have to deal with this problem, and it will ruin your vacation in the process. I was in your shoes last summer.
See this thread for more details:
http://www.trailmanorowners.com/foru...ad.php?t=10265
Dave