We have an Astro that has the game general issue - the engine and transmission are cheated to the right. Check my build thread for more details, but there is a fix.
While I was installing a seat swivel, it was already necessary to make new mounting brackets, since the swivel would raise the passenger seat up too high. While I was making those brackets, I was able to position the passenger seat another couple of inches aft. A couple of inches doesn't sound like much, but on the Astro it makes a BIG difference because the shape of the footwell is very "tapered". It starts out fairly wide (near the doghouse and your knees), and tapers quickly. Moving just a couple of inches farther back means you avoid the narrowest portion (unless passenger legs are exceedingly long).
There are limits, of course: You can't go too far back or the seatbelt shoulder point becomes a problem (i.e. not safe). Also, if you're using the 2nd row, you'll start to cut into the foot room for the passenger in that seat (but most of us are doing other seating things with Westy/RB50 type layouts, so this is less of an issue.
