Parkway SG or Radian?

[westgre]

First, DS is 5 years old, 39 pounds, and 41.5" tall. I need a narrow seat for my 2001 CR-V. He will be in this seat approximately 15-20 minutes twice a week. Would you be ok with booster training this size child for that long? And I don't really want to put a price on his safety, but the PWSG is about half the price of a RN65. I think the Maestro is too wide.
He is using an old style PW in DH's car for two trips a week of 30 minutes each trip. He will be in the boosters only when both DS's are in the same vehicle. Otherwise, he'll be in either the MA or RN.
DH's Civic has RN and PW.
So, either MA and RN in my car or MA and PWSG?
Hopefully this makes sense. ;)

[Joolsplus2]

Safety 1st Go? Your CR-V has top tethers, right? And it's not too bad to install with a seatbelt (lapbelt in the center in that car, right?). Though if it's your 'always the kid in the center sits here' seat, the Radian might be best for long term comfort. Try your old PW for awhile and see how he does in a booster? There's not a lot of room to wriggle out of place back there.
Why am I hung up thinking about 3 across? You have another coming, right? The Go is just so narrow, I love it in my Escape, plenty of room for adult-size kids back there with Leah in hers. O.co has them for 164 right now, too.

[westgre]

I do have three across. DD is in a Literider outboard. Marathon is center. I know both the RN and PW work outboard with that set up. There are top tethers, but no LATCH. So the new seat will only be used when both boys are in the car (infrequently). How is the Go install with a lap/shoulder belt? If it's not too difficult, that sounds like a good option.

[westgre]

Tried DS#1 in a booster for a short trip today and it was a DISASTER! He unbuckled twice! So, the PW is going back into storage and I'm on to now buying TWO new harnessed seats. I did try DS#2 in an Evenflo Tribute, which I measured in the store to be 17"wide. He has 4 pounds and about 1.5" of growing room in the Tribute. How much time do you think that would buy me while waiting on DS#1 to be mature enough to ride in the booster? Or should I just bite the $300+ bullet and buy two tall, narrow harnessed seats? I wish the EFTA (which I already own) or the Maestro was narrower! I really appreciate your help!