I think you should be safe with soft sole shoes. Unlike the Bullet and Passport brands which are built with 1/4" decking materials, your Outback is constructed with 3/8" thick boards over trusses spaced 16" apart. You can use 2" foam boards (cut to manageable sizes - 2'x4') to span across the trusses if you want to disperse the weight. But I honestly don't think that's needed on your coach.
https://www.keystonerv.com/travel-tr...tures-options/