Matt,
If you use the search facility you should find lots of info on this subject, but to get you going:-

I started eribaing in 2003 and have had a rear carrier on all 4 of my vans.As you are aware you just have to ensure you still have a good noseweight. I would also only put two adult cycles on the back.
My previous three were the lower pre 2009 height and had to have the top fixing through the awning track.
On my present van I have gone through the waist of the van. This allows you to still use the back window, keeps the weight lower and is easier and safer to lift the bikes on and off. I decided on this route having seen a poorly fitted example on an Automotive Leisure van. The top fixings had gone down at an angle to clear the long rear grab handle and I realised you could just cut the middle section of the grab handle out to avoid this problem.
Omni and Fiamma do carriers that will/should fit. Fiamma are the most easily available second hand as more have been sold new. Having owned both I prefer the feel/build of the Fiamma. Check the Fiamma catalogue and you should come across the Trigano motorhome model which I know will fit as this is what I bought second hand, along with the seperate mounting kits. Others will do the job just as well/better.
The top and bottom fixings/mounts MUST be bolted through the van sides and steel framework. Although others have used screws for the top I would not advise this. Lots of non setting mastic, eg Sikaflex and not silicon is needed to seal the holes/meeting surfaces.
When you do the bottom fixing you will need a wooden packing strip on the inside of the van to bolt through and spread the load. I have used cherry [when it can be seen] or birch plywood [when it cannot] About 600 x 80 x 20 will do the job. You may also want to cut small spacer tubes a mm or so shorter than the wall thickness to limit distortion when you bolt this bottom fixing in place.

The attached show the carrier on my 2017 430 van.
7 - rear carrier-800.jpg - Bild entfernt (keine Rechte)8 - rear carrier side view-800.jpg - Bild entfernt (keine Rechte)

You can also make a plate for fixing to the front jockey wheel mount, onto which a Thule cycle carrier can be attached, the type that grabs onto the ball.
Again you can find information on this using the search facility

2 - Front bike mount-800.jpg - Bild entfernt (keine Rechte)3 - Premium Jockey wheel-800.jpg - Bild entfernt (keine Rechte)

Pleas PM if you need more hands on information and we can arrange a phone conversation.


Colin