What cars fulfill this criteria?

[Sturmovik]

Another option could be a used Statesman, doesnt have a flat floorpan, but it does have a shitload of rear legroom

[Evo_Lee]

How much is the new Oydessy? They have a flat floorplan throughout, so they say being one of the selling points of the car. Check out the cars in last year's Tokyo Motor show, the theme was releasing functional cars for those with needs. All the Japanese makers retro fitted some models to be released with special features and mechanisms/lifts/swivel seats to enable elderly or the disabled to move in and out easier.

[walkie]

Another option could be a used Statesman, doesnt have a flat floorpan, but it does have a shitload of rear legroom

and is much lower to the ground than some of the others suggested. those new Odysseys are quite low though aren't they

[Captiva Fan]

They're lower than the old ones, but I don't know if they'd be low enough so that getting in would be more difficult than the Tarago. They don't look like they'd have Tarago levels of headroom / getting-yourself-out room though.

This could be an occasion where a Territory is worthwhile, although they've got nothing like the rear seat legroom of a Tarago. The towing issue is kinda irrelevant if it's just a small trailer. I'm not sure about the resale issue, at the moment I reckon the Terrortory would be much better than a Tarago, but after a few years & tens of thousands more Terrortories on the road I suspect they'll drop back to Falcon wagon levels. Mind you, the extra fuel use would probably make up for resale over a few years (we consistently get 10L/100km in the Tarago, commuting from Jannali to Pymble daily).

[CT]

You can option a sliding rear seat for a territory too which may be a handy option in this situation.