I truly appreciate all of the advice, ehellions. This sounds difficult enough that I may wait and try it on the family first. It never occurred to me that the whole thing could just fall apart! Yikes! It looks so scrumptious in the picture!
I have 2 recipes for this, and one of them calls for swiss meringue. Definitely I'll be making it that way. It sounds like a good idea to just assemble it a few hours beforehand. Thanks, PastryGoddess.
It's good to know that I could make the layers a few days beforehand, cicero. Thanks for that suggestion. The last day or so before they arrive will be quite busy.
I don't know the difference between a hard meringue and a pavlova, Katana_G. One of my recipes is for regular "beat it up and cook it meringue," and the other has the mixture cooking over hot water while it is being beaten, and then it goes into the oven. I will make the layers in the evening and leave them in the oven all night. Thanks for that good advice. [That is also the safest place for them in this house with young cats and a tall dog.]
Instant flour is sold in the US, mechtilde, by Betty Crocker [large food company]. It's called Wondra Quick Mixing Flour, and comes in a blue shaker. It makes gravies and sauces incredibly easy to do. Thanks for the potato flour suggestion - there is some already in my cupboard. I also greatly appreciate the crème patissiere recipe. If I don't use it for the mockatarta, I will use it to fill a Swedish midsummer/strawberry cake that I've been wanting to try.
If there is enough time before my guests arrive I still want to make this. Otherwise, maybe I'll try a rolled cake make with potato starch. There are several recipes in one of my cookbooks. Thanks for all the advice - I rather suspect that you all have prevented some sort of kitchen disaster.