I have access to a pond that has no way to get a kayak to it. But I can hike to it so I was thinking of one of those inner tube style things I always saw in magazines as a kid. Anybody know of a modern product like this that can be broken down / deflated and put in a backpack? I can bring my 20v inflator to blow it up. 

Search "Float Tube" on Amazon or Google and you will find many options. I also remember them being much more popular when I was a kid, guess kayaks have replaced these for a lot of folks. 

How about this?
https://www.cabelas.com/p/outcast-fish-cat-cruzer-float-tube?ds_e=GOOGLE&ds_c=Cabelas|Shopping|PMax|Fishing|General|NAud|Google|NMT&gad_source=1&gad_campaignid=20046765526&gclid=Cj0KCQjwrPHABhCIARIsAFW2XBM1TQ-ivi4iJYd2Z5TUybPNV6GEOa7Q94tDg7A3pO3gbdP6gjYJvZQaAnFOEALw_wcB&gclsrc=aw.ds

belly boats are a pain.  Don't forget that you'll need waders and fins with them also.  

 

A pontoon is a better choice to me.  get one with a minimal frame to pack in and skip the waders.  Plenty of options on the market and guys will hike them into high mountain lakes for trout.