My twin daughters are 13 month old now, walking on their own. They're having 2 daytime naps now, always in a stroller outside.
I want to take them out on a bike trip, but had not found a bike trailer that would be comfortable for a daytime sleeping, so that I can plan for more than 4-hour trip.
I've looked online at ones that state to have reclining seats, such as Thuley Chariot Cross, Burleys, TFK Joggster Velo - the reclined angle seems quite steep for comfortable sleeping.
Our travel stroller is quite light at 8 kg, so not inconceivable to strap it onto a trailer, but it would be quite cumbersome, and not sure it would fit in the trunk along with bike trailer.