Know that digital TV is not 100% digital. Let me explain. While the program is encoded digitally which is different these days when compared with old, it still flies through the air on an analog RF frequency. As such, you do not need any special "digital" antenna since technically there is no such thing. Old UHF antennas work just fine.
I have my stick down and have installed an omnidirectional amplified UHF antenna, (often called a UFO antenna for obvious reasons) at the mast head. I need the height due to distance from towers; roughly 50 miles which is right at the edge of the horizon... I have done a similar install on a previous boat so I know it works well for me. Not everybody will need this. For those who don't have the opportunity for a mast-head installation, I think it still quite possible to purchase a small omnidirectional UHF antenna and simply raise it on the flag pennant when you want to watch TV.
To point in your question regarding reception through fiberglass, you should have no issue if you are reasonably close to the TV towers in your area. I found you and it looks like you are about 40 miles from St. Louis? If so, you may find you need some height, although it is worth trying the internal mounted rabbit ears first.