As a soldier all my modeling was always some sort of compromise inside a apartment, garage, tool shed.... bedroon, dining room, balcony

Here in Central Texas (rural so no real codes to comply with) I decided on a out building and my current 16x24 work space /hanger is heated by portable base board type thermostat controlled electric and the cooling is by ONE of the very small walMart window units....

Goal being comfort but more importantly keeping glues, paints, and fuels in a 50F to 80F environment year round

To this end I used a relatively low cost portable building*, wired it myself, insulated and sheet rocked my self, and put solar film on the 4 small and one large windows....102F outside right now and 78F inside with AC on low fan and one box fan circulating the air

* side of the road every where in rural Texas and in the $3000 to $8000 range

Windows and Good lighting are necessary
Bathroom 150 feet away or bushes 10 feet away
Tying into (safely by code) the house 200Amp box with a 60 amp service was NOT that expensive BUT the trenching in Texas Colichi was slow going until son and I rented a Wheel type rock saw...chain type ditch witch is a non starter here

So to the original poster...if you own the property and plan on being there a while...re-purpose the out building is my vote...the added expense is worth the $$$ and effort....can be done in stages as $$$ are available.... small re-frig, small microwave, coffee pot, computer, small crock pot (engine cleaning)

do not have to share space any more with clothes, cars, auto maintenance area, bedroom, dining room, and wife is so happy to NOT smell glue or dope that alone is worth the effort.....when momma's happy EVERYBODY is happy...my opinion