We have a 14 month old and usually are fine with the train and the bus, but sometimes it would be useful to be able to do a short hop in a taxi, e.g. we can't go to one family member's house because it's a few miles and the roads from the station don't have pavements; also when we go on holiday it would be useful to have the option to do a couple of 10-20 mile trips in taxis for exploring.
Our car seat, like pretty much all of them for this size, is much too heavy and bulky to carry along with the pushchair and luggage. We don't want to hire a car on these rare occasions because neither of us has driven for ages, so until we're ready to buy one and do catch-up lessons it doesn't feel safe to suddenly drive on a really long trip with all the motorway driving in particular.
I've found a total of only one Group 1 car seat that can reasonably be carried with our other stuff, but the problem is that it's forward facing (Urban Kanga). If we buy it and just use it for these little hops, I feel nervous that we're just as likely to crash in a taxi and DS won't be fully safe in it. On the other hand waiting until we buy a car or until he reaches 4 years old is going to be very limiting.
How unsafe is it to use? What do others do at this stage who don't drive?