I'm tweaking a Lasagna Bolognese I'm using fresh pasta sheets (boiled al dente), a very slow simmered Bolognese, a whole milk ricotta mixture with a fair amount of spinach, basil, egg and Parmesan and a Bechamel sauce. The thing is, I want six layers of pasta but I don't want a huge pan of lasagna. I'm making this for a (obviously very hot) date. I don't need leftovers into the next millennium. I think I'm going to use my 9" pullman loaf pan (4x4x9 with a lid). I plan to butter the pan then line it with three parchment "slings", maybe one half of an inch between the strips of parchment for slicing. Get it? To make it easier to remove clean slices? After lining the pan with my "slings" I'll butter again then line the pan with Bechamel, then stack the layers. I'm thinking that I will use the pullman pan lid instead of aluminum foil for the initial bake. I will assemble the lasagne the night before and keep it refrigerated it until the next day. 

So here's the question. I've looked at a gazillion recipes for clues about baking temperature, when to remove the lid and what temp to finish. Also whether to bring it to room temp before baking. Of all the recipes I've looked at, not a one deals with such a tall but narrow lasagne. Clues are all over the map and I'm losing confidence. Can anybody advise?
The thing about lasagna is that it really only needs to be heated through.  All of the components (pasta, the sauce or sauces, the cheeses) are already cooked, or don't need to be cooked.

So baking the whole lasagna heats it through and helps the flavors to meld.  

A 4" thickness not tremendously thicker than some more traditionally proportioned lasagnas, so you should expect it to bake through in about the same time any casserole of that thickness would require.  I would start at about 325-350 degrees, for about 1 hour to maybe 1:15.   You may need to leave it covered for most of the baking period so that the top doesn't overly brown or dry out.

In the end, you can test the casserole with an instant read.  It should probably get up to about 150 or 160 F internally to be enjoyable

Lasagna should be very forgiving.