Here's my take on the 51 vs 52 debate from a strictly campervan perspective, with info borrowed from this most excellent blog about the 52https://www.e52lowdown.com/
Interior space: nothing in it when you've stripped it out
Walk through: maybe my E52 will be walk through if I change the front seats....which I might. But not really an issue for me, as I will probably be the only occupant.
Camping adaptations: a pop top is available for the E52
https://www.e52lowdown.com/2022/07/e52-camper-becomes-reality.html. A captain's chair for the E52 has been done by these people. Perhaps their idea can be copied/bodged
https://campervanco.com/product/Nissan-Elgrand-velocity/
CVT gearbox fear: it's unfounded. Just look after the fluid. Driving with the CVT is fine. You don't really notice it.
Decore fear: this put me off the 51. With the 52 the prevailing opinion is that it's just not a worry. And I'm going to LPG it, which I think (?) will cool the cat temp and make problems even less likely.
ULEZ and other fossil fuel restrictions: you can bet your boots that more and more restrictions are coming, all over Europe. So if you want to keep your wagon for 10+ years and drive sur le Continong it's probably safest to have the newest engine you can afford
Motorbike in the back: after stripping it out you can get a bike in easily with a winch. You don't have to crouch in the wagon and cripple yourself....just stand behind it with the remote control and let the winch do the work. I got this idea from these Frenchies:
I'm intending to make the ramp and chocks by adapting used gear from ebay. I'll probably add a strap between the bike and the inside of the van roof, just to protect everything from the strain when the bike wants to lean. I've bought a portable winch. It won't be bolted down. It'll go in the back for motorcycle loading, or be attached to towing hooks or whatever to retrieve the wagon if I get stuck in the mud when wild camping
FWD vs RWD vs 4WD: the 52 is the winner here when camping in the mud. FWD with selectable 4WD much, much better than RWD
Sales success in the Far East: the Alphard/Vellfire have beaten the E52. Some say this means the E52 is not a very good car. But isn't it more about perceived status and looks? Asian tastes are different from ours. Minivans are higher status than limos, otherwise the Elgrand and Alphard would have been discontinued. Some of the Toyotas are stunning
https://en.wikipedia.org/wiki/Toyota_Alphard#/media/File:Toyota_ALPHARD_G's_350S_(GGH20W)_front.JPG The E52 probably looks a bit staid on the streets of Tokyo.
