Adding Trail bike mounts to a Jayco Flamingo

Boc

I looked for something similar for my GU but to just sit on the back like a normal bike carrier. I found these guys in my googling, might give you some ideas

Carrier

I made up one for an Off Road Jayco Eagle years ago for my then XR400. I simply modified the rear bumber which carried the spare wheel and the bike rode there. It was quite simple, actually made it up while working in remote area of the Kimberley and it worked very well. I never loaded up the drawbar with anything as you will be doing but my set up did not seem to upset the ride or towing dynamics at all. Actually it seemed to take a bit of load off the dual cab at the towbar, less ball weight due to counter balancing, and everything travelled well.
No doubt I will be told that what I did was illegal etc etc and I will be told I was silly stressing a "Weak Jayco" like that but I've done sillier things than that in my life. Ideally a dual cab trayback would do the job if the tray could be made longer. Mine was a well body with a canopy!

Last year in Alice Springs there was someone in the Caravan park with a jayco camper that was set up to carry trail bikes - but they had what looked like a 150mm x 150mm telescopic drawbar setup. They had to remove the bikes to setup camp each night.

We carry 110kgs of Honda SL230 on the A frame of our 17ft Evernew van on a length of C section and is held on by 4 tie downs. On the rear we carry 85-125kgs (depends if jerry cans are full) made up of 2x bicycles (45kg incl carrier) 2x 20L jerry cans (45kgs when full which is rarely) and 1x 245/70x16 (35kgs) spare wheel. Our vans now done over 100,000km over all kinds of roads in various conditions, including corrugated dirt like the Gibb River Rd with no problems and it tows well but we do use and recommend a friction sway control device as so much weight is far away from the van axles.

For a bike on the rear I'd think you'd need to run your supports along the chassis a bit (get rid of the current rear bumper) use C section like on the front to sit the bike. You may need to brace the top of the bike solidly back onto the van to restrict movement and help hold it on tie downs on the rear may not work too well. With our bikes on the rear we have them tied back to the van at the top and the bottom to restrict movement, until we did this we had problems with the bike mount cracking etc...

Don't know what size van your got, but what your proposing can be done but be aware hanging an extra 100kgs odd off the front or rear so far from the axles can lead to instability problems. Use of a sway control device will help lots with maintaining stability especially in adverse road/weather conditions.. ie strong gusting side winds. rough undulating/potholed roads.

check out these sites re sway control units
Sway Control devices
Friction sway control unit

UK site - Load the van and see how load affects stability

UK - Towing stability study

Hope this is some help

With the carrying frames you will be adding 250 kg or more weight to your camper. If your camper is a standard model it will only have a load allowance of 300 kg. The resultant loading will leave you with less than 50 kg for cooking equipment, food, clothing, bedding and beer/wine. Can you live with that restraint?

As others have said placing those weights at the end of the body will decrease the stability. As I see it you should get yourself a toy hauler or a utility to carry the bikes.

PeterD