FF high weight narrow carseats

So I bought a Honda Odyssey 2010, the dealers are going to take the middle armrests off for me, so hopefully I can access the back seat easier.

I will be fitting five carseats and one booster in it. Looking for options on high weight, high harness narrow carseats? I will have one who is 50lbs just 4yrs. Not sure what is available, Radian? Evenflo 400?(though I read it has a short harness) Frontier?(Don't know anything about this seat) True fit?(I don't think this is narrow though)? Any others??

Looking to do a set up something like this middle row, passenger side booster, plus one Radian RF with angle adjuster, drivers could be this high weight seat or a RF seat?? Back row generations passenger FF, middle RF Radian or Graco MR, driver's RF radian or Graco MR or another narrow FF facing seat.

Children 1: almost 3yrs less than 30lbs will be RF
2: almost 3 yrs about 32lbs hopefully will stay RF(parents have FF)
3: 20months about 35lbs want RF(parents have FF)
4: 4yrs 32lbs FF in generations
5: just 4yrs about 50lbs need a high weight harness?
6-8: 3 children 7-8 all about the same size will share parkway booster

Current seats Evenflo Titan(just outgrown RF could possible use for a short while FF facing for the one almost 3yr old have to check fit though). Generations, Graco MR than just a variety of boosters. I also have access to a graco nautilas as my sisters daughter is only using it as a booster so could swap her for a booster. It harness to 65lbs right?

Any other suggestions?

I have no clue about fitting in vans for specific vehicles, so if I miss something vehicle related, this is my disclaimer... I'm also not as up on the newer seats and changes to older seats as some others may be.

If you truly need narrow seats to make it all work (I know in the truck we have a ton of room but no idea about vans, as I said), you could look at the Radian, the Safety 1st Complete Air (now to 65lbs as well), Cosco Scenera (though with your age/size kids it would have limited applications).

The TF and Nautilus, and Frontier, are not narow seats though the limits are nice.

A narrow somewhat decent FF only seat with ~16" top slots and a 50lb harness limit is the Harmony V7, it also converts to a (short) HB and backless booster. It's not the best choice for you limit wise but narrow and only $100 at Walmart. If the 4yo was short enough, you could swap the Generations for that. Oh, I was thinking of the newer Generations65, yours might be the 47lb model? so you can't give that to the other 4yo...

Facing the same way, at least, the Radian and MR puzzle well, as do the Radian and Complete Air.

Ack, I gotta run. I hope you get some good responses.