Ok, so I just went ahead and made it just like the Alpha Delta DX-CC, which is a 40/20/10m with trapped 80m. It is also resonate on 15m too. It is setup as a slightly sloped inverted-V. I installed a 10ft 1.25″ conduit as a mast on the chimney, and put a pulley on top so I can hoist up the antenna without to much trouble.
10m leg was 8’4″ from center insulator to fold back point, which tuned to 28.200Mhz @1.2 SWR
20m leg was 16’6″ from center insulator to fold back point, which tuned to 14.111Mhz @1.1 SWR
40m leg was 33’4″ from center insulator to trap, which tuned to 7.100Mhz @ 1.1 SWR
The 80m leg, from trap to end was 3′. which tuned to 3.72Mhz @ 1.0 SWR.
15m was also resonate at 20.9Mhz @1.2SWR.
80m is very narrow tuning, SWR goes up to 6 when moving +/- 100Khz, but I have a LDG Z11 Pro II tuner for the rest of the 80m band.