Thank you all for the comments, friends
As Christmas is nearing fast and I'll have some days "off", the next plane should come in 2018.
@ Erik - right, the fuselage is very thin in plan view. There is not a lot of stress in that direction. The Tigercat has a deep fuselage but it is very, very thin in plan view! I guess that the reason is the same.
@ Papermate - two types of UHU - white and all-purpose. On the wings, it is white glue for the structure and all-purpose for skinning. As you say, white glue on large surfaces cause warping, which would be very bad with gloss paper. I apply the glue directly from the tube. The trick is to proceed step by step. By divinding the task (middle below, left below, right below, left over, right over...), each step requires less glue and less time to apply it. The first step requires a lot of care to get the correct alignment. The others become easier. I don't hesitate to add tabs or whatever provides a better gluing surface and makes each step easier.