Welcome to the gang LG, enjoy here and out in the playground.

I don't have a motorhome so feel I am not qualified to comment and would put on on the back of my van.

If you have no luck with answers here, pop you question into the "General" section of the forum. I would normally say in the "Techies" section but think as I say, for now anyway.

Keep Safe out there.

And it's welcome from us two 2 LG so some big electronics company took your Monica hey hope your getting a nice big fat cheque from them each month lol
You will need to know the weight of your bago when loaded and on the road Firstly ,then you can work out how much extra you can put on the bago if this is ok you should be able to get a unit built that would have the strength to carry your choice of happy wheels. I am no engineer but have built quit a lot of different farm machinery and modifications to them I would guess that a frame with sufficient strength would weigh around 50 kg assuming that the chassis rails are all the way to the rear of the body, plus your choice of ride probably 100 kg or more if it's a Harley lots more. I could not estimate how many gold coins you would need to donate for said frame though. I don't know what truck is under an Esperance but would think the chassis would be able to stand the weight out the back.
But most engineering workshop should be able to advise you on that and build one for ya.
Hope this helps a bit

Lg I should mention that there is a limit to the overhang alowed which is a max of 3.7 meters OR 60% of your wheelbase which ever is the lessor of the two so if your wheelbase is say 3 m then you are only allowed 1.8 m behind the Center of the rear axel so you need to be mindful of this with your carrier