My last 3 TT's (including our current one) were all right at 35 feet, and I don't have any issues. Sure, to someone who tows a 20 footer it would seem huge, especially when it's being our Excursion, but if I put my wife, 6 kids, and 2 dogs into a 20 footer there'd likely be a fatality and everyone might not come home ;). You've got to find the right combination for you.
I find bigger trailers (my very 1st was a 23 footer, so I've towed all sizes) are more stable, but obviously take up more room.
With practice (and patience) , 30-35 feet isn't a problem. However if it was a Los just my wife and I I wouldn't nend as big of a rig. I like looking at my feet per person ratio rather than just overall length - especially when the kids bring a friend or two. Of course I also don't mind "voting a few off the island" and putting them in a tent.
2020 Jayco Eagle 355 MBQS
2011 Ford F-350