Hi!
You will probably be able to get 3 seats in that row. You will likely need to use seatbelt installs for all of them (with tether if forward facing) and it's possible the Extend2Fit might be too wide, though you can give it a try. (As an aside, the Clek Lling is narrower if you're looking for a narrower rear-facing only bucket seat, but it's possible that you don't actually need a seat that thin- just seatbelt installs for the seats in the outboard positions and possibly a slimmer seat than the Extend2Fit if you find it overlaps the center seating position too much.)
Your vehicle doesn't have 3 full lower anchor positions. Instead the center position shares one with an outboard position; therefore they can't both be used at once. Your manual will have this information, and instruct you to use a seatbelt install in the center when there are seats in the outboard positions.
I can't vouch for the Journey but many Dodge/Chrysler vehicles of that era have a cinching (lightweight locking) latch plate on the buckle to lock the belt center instead of a switchable retractor that you pull out to lock. Again, this info is in your manual in the child seat section; you can also test as described here:
https://carseatsite.com/lockingclips/
If you have a cinching/lightweight locking latch plate, the 2 pieces of the belt must lie parallel to remain tight, or else you will use a locking clip or built in lockoff to install. (There are many rear facing only seats with built in lockoffs available.)
Again, you will likely need to use seatbelt for all 3 seats in order to fit them.
You will also need to test for independent install. After installing all 3 seats to make sure they physically fit without pushing each other out of place, remove the one in the center and make sure the seats on the side don't move more than 1 inch in any direction when you pull where the belt goes through the seat. Mark where the latch plate lies (I use painters tape or chalk for this) and remove them. Then install the center seat, again, until it doesn't move more than an inch when tugged where the belt goes through. Now reinstall the outside seats, making sure you get them as tight as before according to your marks.
Good luck!