You may want to try the regular MIK deck. Here in the US, I was told the same thing, after I ordered the deck, but it bolted right on no problems. It is a great addition.
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This is a great bike. https://www.giant-bicycles.com/us/bikes-quick-eplus
Very stable cruiser, with torque and speed when needed. Comes with fenders, lights and a good rack to hang panniers or baskets off of. Get MIK flat top for the rack. It bolts right up. Giant carries it in...
I have the Timbuk2
https://www.rei.com/product/112681/timbuk2-tandem-panniers-pair
Price has gone up but you might be able to find them somewhere else cheaper.
I think the rims are ok but spokes need to be heavy duty. I wanted the new Giant rims because I was going to go tubeless. No so worried about it any more.