Car seat for mazda bongo?

[MummyMacMumFace]

Our car is in the garage for the next week and we have been given a mazda bongo as a courtesy car. However we have just discovered that my son's car seat doesn't fit.

My son is two years old. My 5 year old has a car seat which does fit in the van, and this could be used for either child (it's a rear facing seat with a 5 point harness).

My options are to get a very cheap seat for the two year old, which would only be used for the week, or to get a high backed booster for my 5 year old. I would prefer this option as we will need this in a year or so anyway when she grows out of her old seat.

Can anyone recommend a seat please?

I'd get something like a Joie trillo high back booster, or a Joie tilt if you want to get another RF seat.

Thanks for the reply. We already have two rear facing seats, so I think we would go for the high back booster.