Going from 26' to 33' total length

There are ways to tactfully beg forgiveness rather than ask permission. I'm not advocating becoming a pain in the neck everywhere you go, but the truth as far as I can tell is, many sites in parks are de-rated for effect. IOW, your (my) 34' rig will fit in many spaces ostensibly for smaller trailers, just a question of you showing up and putting it there. There may be National Parks where they come out with tape measures and send you on your way, but I haven't seen one yet. Granted, I don't have the miles some of these folks do, but from our trip out west, there was no place where our trailer even raised an eyebrow. If the limit says 30', it's likely they meant the box, not overall length (wink, wink). What's a few feet amongst friends?

Seriously, a lot of it depends on you and your tact and skill. I don't see an issue. I'm sure others would disagree, but if it fits...it fits. Obviously then, it becomes important to know for certain when it won't. Life is short, enjoy it often.