We are at 28' which is just a bit shorter than what you are considering. As other replies to your post have said, commercial CGs will ask the length of your rig and put you in something suitable (in MOST cases!!). In over 20 years of towing, we have yet to encounter a CG that didn't have a site large enough for our TT and I suspect you will have no issues, either.
Quite frankly, at 28'-30' you will have a much larger selection of sites from which to choose than the folks that went out and bought the biggest RV they could find. I have zero sympathy for those who do so and then whine incessantly about their sites being too small. JMHO
Doug, Linda, Audrey (USN) & Andrew
2008 Sequoia SR-5, 5.7 L, 2000 Coachmen Futura 2790TB Bunkhouse, Dexter E-Z Flex Suspension, Reese W.D. Hitch/Dual Cam Sway Control, Prodigy Brake Controller, McKesh Mirrors
:B