Can you not buff the baron creeps even more?
It is already hard to do anything vs baron push. Game is clown snowball fiesta. One even slight mistake at 20 minutes and enemy takes baron and you can't do anything. Meele creeps are god damn immortal. If you dont have some champion with HUGE wave clear capabilities that can clear effeciently without losing too much resources (e.g. I found Sivir to be basically the only one champion who can stop baron empowered minions waves and supers waves and make it able for team to comeback maybe) you can just abandon those turrets and let enemy take everything they want. And now you want to give damage reduction to casters as well. Like WTF?
You also want to make scaling AD/AP bonus from Baron even stronger. Same for Elder. Maybe first make it actually hard to take those objectives? Taking baron is so god damn easy. This is a huge objective that gives massive advantage. At this point in meta it's impossible to get negative power play with baron. You can't go wrong with baron buff. Baron should be hard as hell to kill. 4 people minimum to do it. Same for Elder drake. I feel sometimes its harder to do rift herald actually than baron.
Don't make this game snowball even harder than it already is. If you want 99% of the games ending under 25 minutes then you are on a good way. Though it will ruin this game even further. Also I think Baron should be just as Elder spawning near 30th minute. That would actually help to create possible comebacks based on ability to play it out slowly.