You could consider a belt sander or electric hand planar? I'm notoriously bad with both tools and ruin things more than fix them, but have seen YouTube videos of people proficient knocking down a lot of rough stuff and finishing off with the surfacing bit.
Hell, I hate my electric planar so much I'd even send it to you for free just to get it out of my shop
Hell, I hate my electric planar so much I'd even send it to you for free just to get it out of my shop