I've used this technique on all of my planes including my 4Star60. Iuse Finishing Resin &micro-balloons for my putty. A glass custard dish works beautifully for mixing the putty with a popsicle stick. My putty is pretty dry.

A tip. After you add the paste to the wing saddle, keep the left over putty (I use a piece of wax paper). Keep the leftover putty with you while waiting for it to set up. When the texture is like frozen dough time to go back and shape up the saddle - eliminates almost all of the sanding.

The pics are from a Killer Chaos 60 build.

pic 1/2 - the initial gap. The wing was set "straight & true" with this gap. no biggie
pic 3/7 - taping the wax paper FLAT- you don't want wrinkles.
pic 8/10 - the putty has been added, the wing mounted and bolted down squeezing out the putty. I used my finger to clean up the joint before any drying - cleans up very easily with alcohol and paper towel
pic 11/12 - the finished wing saddle gap

There will be no need for the use of foam tape or other gap-sealing product.