The electric jacks are great! They can still be used with blocks of wood or stone bricks when the area isn’t even enough and can be fine tuned from right inside your RV. Since leveling is most necessary for the fridge and older RVs can tend to shift a little making the installed bubble levels not 100% trustworthy, I recommend getting a little bubble level that you can keep in your fridge or freezer and level your jacks to that.
Best of luck! You’ll find a lot of advice throughout this forum.
Take care, happy trails! 😀