Why not just use an above the counter micro? Here's one but you can find others.
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Here is a link that might be useful: above counter microwave

You can't enclose the bottom of an OTR, but you can do a faux built in with one. Bear in mind that this is missing the horizontal filler piece across the bottom.

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[Beachy Morning Kitchen[(https://www.houzz.com/photos/transitional-kitchen-ideas-phbr1-bp~t_709~s_2112) by Memphis Kitchen & Bath Designers ProSourceMemphis

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[Beachy Morning Kitchen[(https://www.houzz.com/photos/transitional-kitchen-ideas-phbr1-bp~t_709~s_2112) by ProSource Memphis

I designed the install with side panels, and hung the OTR from a 15'' deep cabinet. The homeowner was supposed to install the filler across the bottom and light rail, but he never got around to it.

live_wire_oak,
Thanks so much for the pics. Why is it that the bottom cannot be enclosed if we would not use the vent or lights? I understand your filler strip across the bottom. Does that allow the homeowner to use the vent and light if they wish? Thanks again.

olychick,
We have looked at those, but there is not much options with them and we like the looks of the OTR microwaves.

The MW needs ventilation from below to keep the electronics cool. It's why you need to use a trim kit when building in a countertop MW into a cabinet, or else leave air space at the sides, back, and top.

live_wire,

Makes sense. Thanks. So as long as we use an OTR in a separate cabinet, and use the front filler strip, we should be good to go? Personally I think it would be handy to have an extra vent and the light. We are going to place it in the cabinet next to the range.

Have you considered a microwave drawer? The people that have them really seem to like them. At least from what i read here on GW. I'm contemplating one myself. Although I use my MW so seldom, I'm considering just getting a mini-sized one to put in my pantry.

You could go ahead and hook a vent pipe up to it too for those times when you've got a rice cooker blowing a bunch of steam, or a crockpot full of brats and sauerkraut steaming all day. Small appliances sometimes need a bit of ventilation, and it beats sitting them on the range and turning on the hood.

funky,
We did look at those, but my wife wasn't crazy about them.

live_wire,
We would probably just use the recirc mode in the OTR.

I'm not entirely sure, but I think the bottoms of OTR units are not flat. They slant slightly upward from rear to front.