Don't co-mingle your funds or use it as your alter-ego since there are sure ways to pierce your corporate veil. 

This must be equivalent to saying no State shall pass a law revoking, invalidating, or altering a contract.Pretty sure a lease is a contract.

I posted on NextDoor with little success, so trying here as there was one post here on BP that seemed to get decent traction although maybe it was the subject that piqued interest. I also posted on DIY forum and that ...

@Christopher HelwigCo-mingling funds and using the LLC as an alter-ego are surefire ways to pierce your corporate veil and lose your limited liabiilty protection, the main purpose of having a LLC.If you want to "consolidate" your activities, I would transfer Title from yourself to your LLC (same or new one which is whole different discussion) and simultaneosly refi into a commercial loan since legal entities are not eligible for residential lending (hopefully you aren't "frankensteining" it).Hope that helps. 

After some google searching I'm having hiccups finding free "official/legal" leases for Colorado that I can alter and use for my tenants.

These past two years have been life-altering and as one chapter ends and another one begins, I cannot wait to see where I am going to be in another two short years.

I'm looking for alterative solutions to separate my physical self from having to collect the cash payments. 

it might be useful to alter or renew existing lease. he had good credit history ,so I hope he will try to keep it clean and move out.

Along with not co-mingling, using the LLC as your alter-ego is another surefire way to pierce your corporate veil. 

Landlord shall not be obligated to clean, decorate, alter, repair, or otherwise improve the rental, either before or after the execution of this lease, unless agreed to in writing as part of this Agreement.