With my truck roof being almost 7ft tall I feel your pain. I have a double cab so although I can hop in the bed for most of it, there is still about 25% I have to reach at from the sides and that werner platform does not really cut it for me.
I have not bit the bullet yet but there is a platform from griots that I think takes you to 30in. I would have to look again to verify. It has a rubber base so it should give you traction when wet vs the werner does not. I added friction tape to mine but now I have to wash my hands every time I touch it to move it because the grit comes off and onto my hands. The last thing I want to do is move my platform and then grab the sponge to wash my truck only to put huge scratches in it.
It is a little more expensive but I think the convenience would be worth it. the only thing that concerns me is how stable is it at that height?