I don't see where the OP was trying to "deal with the issue" here. They were using what is supposed to be an unbiased, public forum to review a problem. They probably had hopes of finding others with similar situations (or better yet find no one else with the same issue) to see how their repair went as well as make others aware of a possible area of interest. Using that data as a gauge, they could then know more about what to expect with their situation.
I think it's perfectly reasonable to ask for the commitment to repair in writing. It's a long trip, with a damaged vehicle in tow. If something were to happen on the way that caused damage to other property it could get messy for the OP quickly. Suggesting that someone can trust a third party based on another person's experience is fine, but it's opinion and will be cold comfort in the event things go sideways. I understand we want to trust, but don't be put off if someone else doesn't feel the same way.
The OP states that he has contacted the dealer and Heartland...several times and seems to be frustrated that they have waited over 6 weeks for a reply. In some areas of the country, 6 weeks is more than 50% of your entire camping season. How would you feel if your 2 year old, $35,000 + camper had a defect that caused you to be without it for one entire season? Now add to that the fact that the defect is reported to be due to structural welds? Would you want to wait 6 weeks for someone to call you back?
Lastly...suggesting the OP check with the NHTSA is in no way "legal advice" and is in fact an excellent suggestion. The NHTSA has huge amounts of data on vehicle defects...what constitutes an actual safety hazard and what doesn't. They're a resource no different from this forum other than they have paid professionals who are experts in vehicle safety, not legal advice. If it was construed as a threat, perhaps we should take a look at our perspective and see if there could be something clouding our viewpoint. If you have a 2004-2008 F250 with the integrated brake controller like me, you have heard about the issues with that unit. I contacted the NHTSA and spoke with an engineer there who carefully explained how the system works and what they were testing (they had hundreds of reports on this issue). That conversation made me feel much better about the problem and how it was being resolved. Good stuff.
Just my 2 cents. Forums like email are emotionless and the reader often picks up emotion that wasn't put there by the author.
Why do people try to deal with issues on this forum. When having an issue with your coach the way to deal with it is by contacting Heartland Customer. This forum is not Heartland Customer Service. Rather than wait for days or weeks for correspondence pick up the telephone an call. Keep calling until you are able to talk to the right person. Keep asking for supervisors. Explain the situation to the factory and see what they can work out. We cannot force the factory to do anything. Try another phone call explaining that your coach is in a shop and has been taken apart to dianose the problem and see if they will not authorize that shop to make the repair if they are capable of it. They will authorize non-Heartland dealers to make repairs but they have to talk to the shop. Have the shop call the person at Heartland who can authorize the repair. Your might be surprised how easy it is if the proper steps are taken.