I'm dealing with a trailer house with about 15 feet of bad floor along
one side. I recently replaced the floor in the water heater closet in
that trailer, and used a wood chisel along the wall. Just that 30"
closet took hours. I'm trying to find a better way. A circular saw
cant get close enough. I tried an angle grinder with grinder wheel,
which worked but filled the whole house with smoke and was real slow.

I do have access to one of those Multi Function oscillating tools from a
friend. I've never used one of them, so I dont know if that would work,
and of course I dont want to rip up the wall either. I did see about a
4inch circular saw blade at the hardware store, I was wondering if I
could put one of those blades on my angle grinder and use that. But I
thought I'd ask if anyone has a better idea.

The floor is made from 3/4" particle board, but will be replaced with
3/4" plywood. (treated plywood by the door, which is where the floors
always go bad in these trailers). However this trailer had a roof leak
(which is now repaired), so that is why there is such a large repair

The goal is to just remove 4" from the wall the entire length of the bad
area, and put down the plywood. I want to get right up to the wall to
remove all the bad flooring and so I have as much of the 2x8 joist
exposed to fasten the new plywood. I may still add blocks of 2x4
between each joist so there is more to nail to.

Thanks