My wife refused to let me let the chillun (now almost 5 and 3) in the Cruiser until we had a good seat solution. We could never get the car seats to face forward in the jump seats and be tightened down properly. I bought an old crappy Con-Ferr seat and restored it, which is now bolted down tight in the back of my 40. The car seats work fine now, as long as they have internal straps. Now that my older kid can use the booster seat with a shoulder belt, I'm going to need to do more work to get this up to speed.
You may be able to find a new aftermarket fold and tumble seat, which would be better than a con-ferr seat. The back is too short on the Con-Ferr for comfort.