Let me preface this with, I don't know if this belongs in general hammock talk or do it yourself.
Last time I went out camping, we ended up passing on a couple of spots that to me really looked like great places to camp. The issue was sap on the trees. I mean on a couple, it was like a river flowing down the tree. Neither my daughter or I wanted to deal with sticky, possibly ruined straps.
I had an idea that I could make just a couple of sheets of ripstop or just plain old nylon maybe about 6"x40" or even up to 60", and use those to wrap around the tree, and then wrap your straps around those. That would keep the sap on the one side of the nylon, and keep it off our straps. It would have made the first spot viable in my opinion. My other thought was maybe to sew in a loop or two to make sure the straps don't slide down on the nylon. I also thought that their own bag would be a nice addition, or maybe even sew them so they fold up into themselves and you have a cord to cinch them up. It wouldn't make sense to store them with the hammock and straps if they have one side with sap on it.
My thinking is that these are expendable, and things like rips or tears are tolerated to an extent, then when they seem to be used up, just toss them. I would much rather have these shredded than sap on my straps.