These trails are great precisely because they're marked. After crossing the channel you can get lost in these trails for hours. In many places fish scatter in front of your boat as you glide through sea grass channels. I caught LOTS of mullet here, but nothing to brag about. But then my friend was much more interested in paddling than fishing.
This is a great destination for a day paddle, especially if you like to fish. Bring a GPS, you can get a map in Port Aransas or print out coordinates. Be prepared to fight the coastal winds at times. An anchor is great for fishing or eating lunch. Also be prepared for low tides. The oyster bed can tear up the bottom of your boat, or your feet if you should have to walk it.
No accommodations at the trails, but plenty of cheap motels in Aransas Pass or Port Aransas. We paid a a bit more than I normally would to stay at a place on the beach in Port Aransas. The ferry wait was no more than 15 minutes the multiple times we took it.
No fees or permits.
Google Lighthouse lakes. The put in is between Port Aransas and Aransas Pass.