Up plating a fairford

Ive sort have known for a while it’s possible to have the gross vehicle weight of our fairford increased? and aft considering this, I had a quick look at the SV Teck  web site and understand I have to fill in a technical form to get a quote, can anyone confirm through experience what the likely cost for up plating would be? I’m assuming I can go from 3500kgs to 4500kgs based on something I read on this forum.
Any pointers appreciated.

We had our Fairford up rated to 4500kg by SV Tech. I think the cost was about £300.
I filled in their form the best that I could online and phoned them. They done the paperwork and nothing had to change on the vehicle other than sticking on a new data plate which SV sent.
It also reduces your road tax but make sure your driving license covers you for above 3500kg.
What’s your reason for wanting to uprate, if you don’t mind me asking?

We’ve outgrown our door mounted bike rack, the next step would be a tow bar, a heavier bike rack with the heavier bikes, I suspect we will be over the existing 3500kgs
I have C1 and have quite a few birthdays before reaching 70, I have some potential health issues and need to check these will not be reasons to take my C1 entitlement prior to reaching 70.

If you’re just putting heavier cycles on the back, you might not exceed the weight limit?
I’ve attached a pic of our Fairford weigh bridge tickets, front axle (1660kg), complete weight (3720kg) & rear axle (2040kg).
This was with the 100kg scooter, approx 50[You must be registered and logged in to see this link.]kg rack, full water (which I dumped after weighing), full fuel and loaded for 3 weeks in France.

Thanks for the reply, although I’m a bit confused, if I’ve read your message correctly your bike and carrier weighs approx 150kgs, so if we remove that your gross was still over 3500kgs, is that correct. If so I suspect our current set up with our bikes on could exceed 3500kgs if we’re not to careful with the wife’s packing.
Or have I misinterpreted something?
Thanks again in advance

Probably my fault and should have explained more. When the van was weighed we had at least 150kgs between scooter & rack. Two cycles on the cycle rack, a stand alone air conditioning unit inside the van, inflatable canoe, 2 man tent & camping gear, BBQ & outdoor kitchen, general paraphernalia, full water, full fuel, food stuffs, everything we would need for a 3 week trip.
Maybe you'd find just a towbar & heavier bikes wouldn’t take you over 3500kg 

I think I’m going to have to go to the weigh bridge otherwise I’m just guessing, thanks for your help it has been useful, one other question I notice on the fairford and other van conversions must be the same, the gas pipe to the external bbq point passes along the underside of the rear cross member of the body, did this pose any problems with the tow bar installation?

The scooter rack slid into two receptacles that were permanently bolted to the chassis, so I never had a towbar fitted.
When I wasn’t using the rack the two receptacles could only really be seen by getting under the van.
The gas pipe, in my case wasn’t an issue.
[You must be registered and logged in to see this link.]