Interior non camping fitting rear 3 point belts

Seatbelt Fitting

Caravelles have pre-existing holes and threaded nuts awaiting your 3 point belt. If you have a factory converted camper the chances are it left the factory as a panel van and you will need to add your own mounting points. You can tell if your van is converted as the windows in the rear will have a squidgy bit of rubber betweeen the outside panel where the glass rubber sits and the inside panel which will have a plastic covering strip to hide the edge where the hole for the window was cut.
It is easy to find these existing threaded anchor points - they are usually fitted with a threaded dust cap - see photo below. By carefully feeling along the lining (or removing it), you will find a depression where the cap is located. The cap can be unscrewed with a cross-head driver. Here is the MOT requirements

3 point belt without lower mount

Securon do a belt that can have the retractor mounted at any angle. There is no lower mounting point so they do not need the interior to be cut. These are by far and away the tidiest option to fitting. The part number is 514/30 it has nearly 270CM of retractable web so should be plenty long enough. If you order a belt from just campers they will supply a seat belt CV500 which has the lower mount and will require some modification to your interior to fit. These are sold on eBay but it may be worth asking trade parts suppliers such as Unipart / TPS/ Euro Car Parts.

Securom seatbelt layouts

Securon Fitting extras 514

Note: In this picture the plastic cover which fits over the webbing retractor has been removed.

Middle Seat Seatbelts
There are at least 2 approaches to fitting middle seat 3-point seatbelts. If you use the original double (2 person) Caravelle seats, then they are fitted with lap belts as standard. These can be replaced with 3-point seatbelts; the seat next to the window can use an anchor fitted to the side panel (C pillar) in between the windows. Some T25s were factory fitted with captured nuts providing a seatbelt anchor point. (see photo below)
If not, then these need to be added - a kit to do this is available from JK.

Rear Seatbelts

As mentioned above, pre-existing threaded anchor points may be available. The photos below show their location. You can fit the lower anchor and bring the belt up to the top of the board as shown in the 1st photo, or with a bit of cutting and fitting, you can do the same as the WhiteStar install shown in the second photo.
Photo 1: Caravelle install

Photo 2: WhiteStar install

The lower anchors are shown below.