I would say 6300 would be about the upper limit. The 32' with a short wheel base Expedition is also near the limit. We wanted a Coachmen that had a separate bedroom in the back, but it was 6300/32' and we decided against pushing the old Expedition (160k). I bought a scan gauge so that I could monitor the transmission temp. We also are planning a 6,000 mile trip out west in the spring. How you plan to use it may dictate how close you cut it. Just make sure you have a good WD hitch with sway controller. The longer the trailer the harder it is to control sway (unless you have a Hensley).
