Well I took at a look at both front seats, they would probably swap over but there's a indentation on each for the seat belt, that might mess things up, plus drivers seat has lumbar adjustment, never use it, under the bottom cushion there a large thin steel plate,I can get my fingers in between the plate and the foam from underneath , if I could get some dense foam from fabric store might work to reinforce bottom of seat, kind of a hassle thou, maybe a nice cut to fit foam on top might help.
Yesterday I sat in the van for an hour waiting for my wife, she show up and on the drive home my ass and right leg started having a sciatica type pain, guess I'm just getting old! did find a pictures of seat.

 

I would be more inclined to take it to a trim shop and have them replace the foam in the seat. They might even have something of better quality than the original that might work better for you. Even if you did it yourself its probably easier to replace the foam than to swap out the seat bottoms.

 

Thanks may have to do that one day, I did some research and apparently truck drivers suffer from this issue along with taxi cab, Uber drivers that do long shifts, automobile seats are all designed with a rearward slant for driving, they say to have seat bottom as level as it can be and have seat back as vertical as can be, this reduces the pressure on tail bone where sciatic nerve is, that nerve is what causes the but leg pain.
For now, I bought a memory foam gel insert pillow for my wife a while back and she does not like it, to hard for her issue, so I tried it in the van and its good but to wide and to thick, so I used my electric knife to trim it to seat and reduced its thickness by 1/2 inch, fits perfect and comfortable.
Free for now lol.