Travel seat for when DS outgrows Uptown

DS is nearly 4 and 33lbs, 39", I just moved the Uptown harness to the top slots. We could have 6-12 months left. It's our travel/spare seat, and I'm thinking ahead to what to use when he's too tall for it.

MIL's car is easy - new car/LATCH.

My parents car in Australia is difficult- 1999 2 door civic, no top tethers (need to get those installed), center lap only belt. I've been able to get the Uptown installed RF and FF without any problems and get 2 people either side when we car share. I also take the Uptown on the plane, but QANTAS only allows that to the child is 5 years old, over 5 you can't bring a car seat on, so it will have to be checked.

I thought I would get a Radian for travel, but without trying I don't know if it'll fit in my parent's car - and trying to figure that out at the airport after a 14 hour flight and jet-lagged, won't be fun.

Another option is to get a booster in Australia and use it with this Britax harness - Britax allows it to be used with a booster seat, and it can be used with a lap belt or a lap/shoulder belt
http://www.britax.com.au/Websites/Business/brproddb.nsf/LUPages/Child Car Seats-Protecta Harness
If I did this, I would leave the booster seat and harness at my parents. We visit once every 12-18 months. I intend for DS to be restrained for years.

What would your opinion on this product be?

I still might prefer a 5 pt-harness, I could always buy a Nautilus, check it for one trip with crossed fingers in the original box and then leave it there for future visits. Mmmm, if I could get a deal on one, say around $100, this might be the best option. 6 year expiry, if we get it for the trip after the one in 2009, say for a 2010 trip the harness and highback won't expire until DS is 11 and then no back for 3 more years. I can also see if the Britax harnesses (there are 2 different products) could be used with the Nautilus in booster mode - that would be great for when we get to booster age. It means I'll have to get an extra car seat for travel/spare in the USA - but I don't mind buying car seats!

I am a little confused on the Britax option - so I won't comment on it. Hopefully a tech will chime in.

I suggest your check the Radian Successful Installation Thread (see below)

http://www.car-seat.org/showthread.php?t=18235

I see lots of civics listed, but none specifically your model year. I do see at least one that is older than your car. But, someone else who is more familiar with the models might be able to tell you if it would also be compatible with your parent's car. Is the Civic a universal model or would the Australian version be different than the US version.

My gut feel when I read your thread was the Safeguard Go Hybrid Booster (5 point harness). http://www.safeguardseat.com/go/why.htm. Because it is so compact for travel that you could carry it on. But, it needs a top tether anchor.

I know Australia is big into tethering - you might be required to use a top tether (like in Canada). If you can legally ride with no top tether and cannot get one installed, the Radian performs well in crash tests even without a top tether. It folds for travel, but is not light.

I think the Nautlius idea is good too, but was gearing my suggestions to ones that would not require two seat purchases or checking a seat (other two could be carried on)

I was thinking of the Go as well. I'm visiting in May 2009 and the Uptown will work for us then. I NEED my father to get top tethers installed. They do have retrofit stations for this - I can send Dad the relevant information and hope he'll go and do it, or organise for it to be done while we're there. I could buy a Go and take it with as well as Uptown, so I can see if it'll work in their car for future visits.

The only snag with this scenario is that we normally get a shuttle van to the airport, and they don't have top tethers (I don't think they do). Do taxi's have top tethers? I've seen some taxi mini-vans. I wonder if the Go lets you tether to a seatbelt in a row behind. We normally get a private shuttle van, so have spare seats I could attach the tether to...have to look into this.

It'll have to be a seatbelt install, which I know is a little tricker. DS is short though, so I think it would give us some time of use to get money's worth.

The Australian Britax harness is something that they allow with boosters. I think it's like the 86Y harness. It has to have a top tether, the harness goes over child chest and the seat belt gets threaded through it (I think). It ends up being a 4 point harness rather than 5 point. Some Australian boosters have anti-subamarine clips, for the seat belt to go through. It might be an option when he's out of 5 point harnesses. The Britax harness has a 59lb limit - I don't think DS will ever by 59lbs.