Having a seat that you don't fall out of usually means a set with arm rests. Those can be fixed or movable but in just about every case, the already narrow clearance between seats will be reduced. You could change just one set to minimize the space impact but your better half might not be fond of that idea.
On my 208, I stand and lean more than I sit but I I also wanted a higher seat when I do sit since my center of vision was blocked by the top frame of the windscreen. I looked and looked for an adjustable base but couldn't find one with a D base and also didn't need clearance below the base.. I used to put an extra cushion on top of the original cushion but that was not ideal for several reasons. I toyed with the idea of having a thicker cushion made that would snap in like the original just taller.
I ended up getting a fixed extension (6 inch rise) that I cut to the the size I needed