I'm in the design phase for my new 6000 foot shop in Minnesota. I'm planning on in floor heat, but need A/C too. Not only will it make the humid summers feel better, but more importantly, it will help with keeping wood movement steady and prevent failures when my furniture goes into cooled houses with much less humidity.
I was thinking a mini split system, but would like to hear any other ideas or systems that work well. I've never used a mini split before so any advice would be great.

The general rule of thumb for commercial is 1 ton (12,000 btu/hr) of cooling capacity per 400 square feet. I have 5600 sf with a 12.5 ton rooftop package unit and I leave it set at 75. On super hot days it'll creep up to 78-79 with machines running.

You can get a package unit online and install it yourself. You should be able to get a nice Rheem unit for under $5000.

Don't forget make up air for the spray booth. You'll need something with quick recovery that the in-floor heat won't give you. You'll also need one whale of a good filter system for the AC return air.

I am in northeast Iowa and find that adding humiditiy in the winter months is more important that dehumidifying in the summer.

Gary is indeed correct. The dry winter humidity can easily be under 20% RH in an unhumidified shop, which dries to about 4% MC in the lumber; this is called air that is at 4% EMC. Customers' homes seldom go under 30% RH, or 6% EMC, as a home has moisture added from cooking, showers, plants, etc. and maybe even a furnace humidifier. The summertime humidity when air conditioning a shop will closely match a customer's conditions, but even with a/c it will be close.

Thank you for the replies. I am definitely adding a humidifier to the shop for the winter months to keep the lumber stable and to more closely match customers homes.

From past experience, when we have high humidity for several weeks in the summer, the lumber has too many issues so I do want to have some dehumidification for the summer months. Plus A/C will make working in the summer nicer too.

My friend is a business owner, to maintain the climate in his store he takes the help of http://morrisairconditioninggroup.com/ for any kind of emergency air conditioning service Morris county NJ he always take the help of a professional team and maintain the indoor air quality. You can also take professional guidance to find the suitable unit for your place.

I also am taking a gander at placing in a halogen radiator so would be keen on anybody's experience of these and suggested sizes. I decided to install this specific heating unit because I compared the pros & cons of variants of systems discussed in the resource below.

https://www.heathome.org/