I own a Fox Mountain 5th wheel. Never owned a TC. The idea is intriguing but after having the room in a 5th my DW and I just couldn't do it. I can vouch for the well built Northwood chassis. It has all the right bracing welded in above the spring hangers. Our 5th only has a dry weight of 7300+lbs but has a CCC of 4315lbs. Nice thing about 5th's over TC's is the holding tanks. Even though ours aren't huge they're still bigger than TC's. We dry camp most of the time and having larger holding tanks is a big plus.
Alaska is on our bucket list. We would have no problem taking it to Alaska. We already have 10,000 miles on it and it's holding up perfect.
JMHO but if your looking to get a small 5th and looking at Northwood products I would suggest taking a look at the Arctic Fox 27-5L. Huge holding tanks, more room inside still under 30'