(In case it opens other options, I am a USMC veteran.)Thanks!

Alternatively you can sell to an investor but the investor buyer usually has plenty of optionality in the markets that don't reach the transition phase which eliminates most negotiation leverage.

If I live in a $600k SFH and have around 50% equity but want to "upgrade" to a $900k SFH, what would be the best option?

Agreed, in 15 years I've never really attempted to go after the wage garnishment, but now I'm looking at the option to see what the process looks like. 

@River Sava may be able to help you as well for financing options.  

My team and I are wholesalers who focus on finding rent-ready properties under 100k (typically in popular section 8 regions).

Then at the end of the month/quarter you just have to do the math to deduct their usage from the total and bill it how you want.Best option for me going forward is to simply not look at properties that aren't individually metered already haha

Sales volume in the GNO area typically peaks in June, and then demand begins to drop.

There will be multiple options that will get you closer to your investment goals. 

To give you some background, I'm an investor developer, where we do land development projects typically for multi-family housing.