What features are pushing you to 28 / 30 footers? I have a 31 footer (35 w/tongue) and have found a few spots that make me appreciate the value of a shorter TT. I deal with the length because the unit has all the comforts to make any stay anywhere relaxing to us - which is the point for us. If I where "event camping" as you describe, where the TT is more a place to crash at the end of a busy event day, then I'd be more inclined to have less amenities / extras (extra space) in my TT and keep it as easy to tow / park as possible.
Just a some food for thought, here's one with 2 bunks for the kids that's under 25' (maybe 26/27 w/tongue) and just might be light enough to not even need WDH:
http://www.forestriverinc.com/TravelTrailers/MicroLite/default.aspx?page=floorplandetails&floorplanid=2992
