I used to do hard money lending but I'm not actively seeking these opportunities, at least for now. 

I'm active in Berrien County, just South of your target.

BiggerPockets Family,I am active duty Air Force currently in Denver, CO but am about to move between December and May 2019.

My wife likes managing things and is super organized so we are looking to be a little more active in real estate. 

My question is how I can keep contact with these people in the mean time to keep that relationship, or if I would be fine just getting back in touch with them at that time when I'll be actively looking?

Still passive income, even if actively participating. 

There are a bunch of vets and active duty here plus plenty of others with no service connection who will gladly  share their knowledge and experience.You’ll definitely have some options as you begin investing.

It could be business income (Sch C) or short-term capital gain (Form 4797), depending on your involvement and your other business activities.

You can rollover any other retirement plans you may have into it, with one exception: Roth IRA.It has been discussed at length many times here on the forum, here is a link to one of those discussions for you to learn:  https://www.biggerpockets.com/blogs/2810/21298-sol...There are several experienced professionals including myself that you can find who are active forum contributors, check out responses and see whom you wish to contact to discuss your situation in details. 

I've received dozens of calls and inquiries, but thus far they all have either had a very low income (rent would be over 50% of their net income) or they have a criminal background.