Denver elevation and SLC are about the same - so your comments are very understandable
50's hauling 18 lb models is a bit --well -- optomistic.and up here - a no go setup for decent 3Dstuff
Here is a easy to do -unscale project .
Get one of the new H9 LiteSticks - a couple of hundred bucks I think.
buy, beg ,borrow or rent - a 40 gasser .
This setup will give you a model of 1200+ squares and a few lbs lighter than your previous attempts.
This is not a recommended setup for blasting around the skies ---but will give you a good 3D power to weight setup -
For Denver -you will have something that works

any gasser which will spin a 20 x8 at over 6000 will fly it well .
If you are good at conversions -make yer own -
I did a few cloned Midwest Extras - (same size -but my own construction) --they ranged from 11 lbs to 14 lbs .
It can be done but the constructuion is not like the kit -
No carbon needed either .