My wife and I own a "second home" in Reno Nevada which we purchased with 10% down and were planning to purchase another one, but our lender told us that we can't get another loan for a second home within ~100 mile radius of an area where we already own a second home/primary residence.

Purchase price of $1.1mil, and I am planning to put in some work into it ($200 to 300k) since the house hasn't been renovated for over 30 years. 

But there is a glitch in your plan. 

This would allow you to eventually plan strategically to move into the new house and convert your current primary into an investment property... to then 1031 into your next project(s). 

The lease (with the current college students) was just renewed through their 2025 school year.I'm trying to figure out how to make this happen with little-to-no money down, as I have other 'irons in the fire' at the moment.I'm planning to offer $400-450k for the home, and am trying to structure something where a conventional lender would loan an amount that would be covered by the current rental rate (lets just say $300-350k)...   ...then, anything outside of that amount, would be carried by the Seller (for a short while)...   ...Seller financed with a ballon in 5-years?  

How you proceed will depend on a few factors:- financing will depend on your exit strategy - you'll be best off if you can decided the exit plan (LTR, MTR, or STR) before buying- Since you're not employed and living on savings, what is your burn rate and your cash runway?

I am able to put an extra payment on the principle every year in order to chip away at it early on, but i plan on getting out of the military around the back end of 2025.

Also check out your local chapter of NARPM if you plan to manage houses.  

I plan on rehabbing the entire property to BRRRR or flip it.

In either case, you'd need to plan for a 15-20% minimum down payment depending on which route you choose to go. 620+ FICO.