When I did ours I didn’t bother with a template. They are so flexible it was easy to cut to fit them. I also put some on the sliding door step and on the lid of the box the dog uses as a step to get to his bed on the passenger seat (and we use for books/maps, etc).
I used the 150cm x 80cm mats. The offcuts were handy for the bottoms of Ikea Skubb boxes I have as in the bench seat drawer, to stop rattles and clanging (it’s where I store my pans).
As we have a self inflating mattress for the bed downstairs I removed the Cali parcel shelf foam, lifted the shelf to allow more storage underneath and put a marvel mat on the shelf. That works better for us.
The mats fir perfectly and I didn’t need Velcro to hold them on the floor, but did use some dobs of guerilla glue to fix the bit of mat on the sliding door step.
I’ve found that they vacuum really well (at home), will take a good shaking and/or robust brushing (whilst travelling) and can be washed with a damp, soapy sponge/cloth (anytime).
This little brush and dustpan does a great job on these mats (as well as everywhere else in the van), is nice and small to store, is good quality and great value for money.
https://www.amazon.co.uk/dp/B00940DUEK/?tag=eliteelect-21