I am unsure it will be worth that amount but the area is minutes away from a new major development. sq footage is about 2550, age 45 year old building.

Office will still require square footage, which means cost.

They have a phone app where you can check in on any of your cameras.There is no monthly fee, it records directly to your camera server (I use a laptop) and you can access recorded footage whenever you like from your camera server.They have all kinds of cameras for different needs.

Front and rear doors, 7 foot ceiling height, seperate electric meter, egress from sleeping area, and I think there is a sq footage requirement in that zoning.

I'm would think your rental is current and in good standing.Properties with the same bath and bed and land.An appraisal is just an opnion of value so if you can show a different picture and nicely give the second appraiser these comps that you found you'll likely get a higher value.Also remember that most value is improved with additional SQ footage, new bathrooms, new kitchen. 

If you have a solid chance of getting it permitted it can also work in your favor by getting a discount on that space since it isn't (yet) legal square footage.

Your best bet is to get a realtor or appraisar with access to the mls to pull comps for you.What you really need is sales from the last few months on very similar property ( same # bed, bath, similar sq footage, same size lot, similar age of house within a very short distance from your property).

If you can add an easy room (study, den, patio, etc), add easy square footage, or get a property that needs sweat equity, this allows your to continue taking the new earned equity out, and redeploying it for future investments. 

I have read that a bathroom is one place that putting a higher end flooring in can make a difference and keep the cost low because of the small square footage.

You offer what you feel the property is worth based on similar size (beds and baths and interior square footage)/style/condition homes in the area.