Need help with booster decision

Due to my son being a giant he will have outgrown the Regent by harness height by age 4. So we are going with a booster plus the Y86 harness. I went shopping today. I can get a Sunshine Monterey for $120 or a Recaro ProBooster (from a local store that sells returned items but this one is NIB) for $75 or I can do a toys r us trade in thing and get a graco backless turbo booster for less then $20.

We already have a Sunshine Monterey for the main car. He will probably ride in the other car maybe once every 3 to 6 months but it will be on a basis with no notice and therefore not able to transfer the Monterey to the other car so we need a complete set up in the other car.

I know nothing about the ProBooster except I can buy one cheap.

My son is tall and wide. We tried a high back turbo booster and we have to have it extended all the way up already for him to get the belt to fit correctly and he complained his shoulders were squished.

So do I get another Monterey, a Probooster, or a backless turbo booster? We already have the harnesses for both vehicles but I haven't tried fitting them together with a high back booster yet. I will probably post another thread when I get to that ponit.

The Monterey will give him the most room and I would skip the turbobooster. I don't have any experience though with the harnesses so I will let another tech. chime in concerning that

I bought the Monterey. Now I have to figure out how to use a harness with it.

The Monterey would have been my choice, too. It fits big kids wonderfully.

You might consider looking for an original Frontier (not 85) on swap; it adjusts even taller than the Monterey and my giant 9yo (58" and 100+ lbs) still fits in it when he's barely squishing into the Monterey anymore.

Best of luck with the 86-Y! I know there are a few techs on here who have experience with them, but aside from seeing one for about 30 seconds once, I am not one of them.