I can tell you if launch from Oregon side of the Snake River below (Hells Canyon Dam) you can fish with either a Oregon license or Idaho license. If you park your boat and are on shore fishing, lets say (Oregon) side you need to have an Oregon license. You can be parked on either side staying in your boat and fish, you can have either states license. I would think it would be the same for all bodies of water with borders? I think it would be the same for boats to? Idaho,Washington,Oregon all have the Snake River for a border.
I think the Idaho F&G is strapped just like everybody else. I've been checked by IDFG in the central Idaho high country, miles from any roads. On week a day, good thing I had my license with me.
We all need to help out our states, and take good care of our inheritance.