Most people would agree, they would like more space in their TD. Giving up 2 ft of an 8 ft platform is a significant reduction. Depending on how you build, this might mean your sleeping area is restricted. Most people would like to use that space for a galley or enclosed storage.
In addition, your putting a porch in the front means the tongue, trailer jack, safety chains, the hitch and anything else in this area are in the way when sitting/standing. Depending on the canopy size, there may not be enough room when the TV is attached. Making a relatively good water seal to the TD might be hard resulting in a wet porch.
Also, the towing vehicle (TV) might not be hitched to the TD or parked directly in front.
Your idea of storing various items there is good. Making attachment points for these items and sitting there might not work out. Also it means they have to go somewhere when the porch is in use.
As above, adding a canopy or awning and chairs might be simpler. Popup are pretty light, inexpensive, easy to setup for 2 (can be done by 1), can have side panels for rain or sun.