I have been considering this and to your point, most of the K1s are lightweight.

I needed something extremely lightweight ... so I found https://www.landlordstudio.com I hope this helps

Titanium is great, lightweight to carry too.

Here's a '78 one we're trying to remodel right now:The roofs were a rolled metal material laid over a very lightweight and flimsy 1x2 and 2x2 truss system that was extremely fragile and vulnerable to damage from falling tree branches, hail, and if a repair man didn't know how to walk on them the trusses were easily broken. 

We're focused more on asset management, including robust income and expense tracking and lightweight accounting. 

I have never used that service for a trust, but I know NOLO for rental documents is a little light weight and other generic online services for LLC setup etc can cause companies to have to change their articles later.

That said, those lightweight coverlets (have used Mezzati brand) also go through the wash each time; can dry on a rack quickly or under the fan in the bedroom if damp.  

I'm a recent computer science graduate and I built a light-weight commercial real estate focused CRM tool that works right from Outlook.

@Shawn Jacobsen starting with a lightweight form which may not feel like it is as large of a commitment as downloading an app makes sense.

You may be able to pour light weight concrete with reinforcement glass, like fiberglass over the whole floor, but this will raise the floor too, needs to be done professionally and will cost more but will give a solid surface.....but you still have the joist problem and either concrete or floor leveler will crack.