You'll put so much work and money into it, that you'll never get it back. I've seen so many guys who are auxiliary fire, police reserve, et cetera, make modifications onto their personal vehicles. And actually, most full time cops & firemen don't get to take cars home, so they wire up their personal cars in case they get called in. At the end of the day, they find out that all of their goodies actually decreases the trade-in and resale value, because the dealer or next owner will have to do so much to return the vehicle to stock. Sure, you take out all of the flashing lights and siren; but now there are clipped wires and holes everywhere. Your best bet when you want another car, is to try to sell it to some other guy on your department. Plenty of guys have alimony, child support, gambling problems, drinking problems, kids in private school, spend all their money on girls........they can't afford a new car, and will be glad to buy yours, with all the lights and siren, at a good price.
Go ahead. Drill holes. Cut things off. Do whatever you need to make your vehicle functional.