Do you think Devanti dehydrators are also ok? I found a deal on one with stainless steel racks 10-trays.
I'm not familiar with the brand but I took a quick look and it seems like it has two of the features which were most important to me: trays you could pull out and that didn't have a hole in the centre (i.e. circular dehydrators) and temperature control.
Do you have a recipe for the tomato sauce you make yourself?
We only make it to preserve it, so it's not seasoned at all: https://nchfp.uga.edu/how/can/how-do-i-can-tomatoes/standard-tomato-sauce/
For oily meals, is it actually possible to just take oil/butter/fat separately and add it to the meal when you prepare it? It's kinda interesting that lots of camping meals are low on fat because it doesn't dehydrate well, but at the same time fat can actually keep long by itself and is calorie dense, so you would think it would be good for hiking.
Yes, you can bring oil with you to add to meals. My brother actually cooks in the back country and he brings oil to cook with. I agree fat is good for hiking - I eat plenty of nuts.