Ours is under the bed, the fill hose is attached to a fitting on top of the tank with a hose clamp. The hose is about a foot long, yours should be similar.
Here's a picture with the mattress pushed out of the way looking down into the access hole.
I replaced our leaking pump this summer.
Hope this helps and let us know.
And welcome to the forum.
I was able to access and replace the 36" long fill tube along with the vent tube by removing the carpet covered panel between the left side of the bed and the bathroom wall after I extended the bedroom pop out.
The plywood panel is held in place with wood screws.