It's been said before, but you're also going to want to buy a cheap durable RTF trainer like the Easy Star to get you in the air. If you already have a TX/RX then an ARF would also work.
Imagine trying to learn to drive on a car which flips over if you go slower than 60 miles an hour.
I don't know how familiar you are with the F-117 but you should read about what a nightmare the real thing is to fly even with fly by wire assist.
How much modification has been made to the kit design I couldn't tell you, so it's impossible to know if the kit you have will have a similar level of difficulty. When you start adding weight to a airframe, you change it's center of gravity, so you'll have to be careful about where you put the increased payload to counteract the increased weight of the larger motor(these size/weight increases can easily snowball.
A plane with dihedral and a center of gravity below the wings will be easy to fly and stable. If you want a UAV for photography, you want something that moves relatively slowly, which is bad news when your airframe has a high stall speed.
What fun is a UAV with a 3 min flight time? Those inefficient ducted fan models have short flight times to begin with. It will be worse after adding more weight.
This is probably a dumb question but did you account for the drag of the airframe with that estimate? It sounds like you've got this covered, but it never hurts to ask.
If the cost and durability is the same as the EasyStar, the learning curve would be steep but all other things being equal: sometimes the tool you have available right now is better than the ideal tool which you don't. Time is money and all that.
Link the kit
Put the in kit specifications into the spreadsheet here to check viability. Everything is explained within it.
If everything stays green then it will be possible to do what you ask (although it might not be easy).
If you see yellows you are in for a fight but it is possible.
If you see red then the components pass the flight limit of 0.15 Oz/in (67g/dm).
Personally I wouldn't recommend using your F117 straight away as a FPV setup or a UAV as its your goal so crashing it won't be fun. Get a simple safe plane to practice flying while you build the F117 that way you might actually have a chance to control it when it goes south.