[Elecraft] KX3: LNRPrecision EndFedz EF-10/20/40KMII Antenna SWR tuning

[Esquer Dave]

Newbie KX3 owner ALERT
LNR Precision EndFedz EF-10/20/40KMII Antenna SWR tuning help needed (kind, constructive, helpful discussions/words please)!

					Measured SWR (2 measurements at 2 different times of the day)
Mhz		At SO-239	after 26' coax	after 41' coax run	
7.0		1.35			1.1			1.0
7.125	4.0			2.5			1.5
7.3		10.0			6.0			2.0

14.0		1.5			1.2			1.5
14.15	1.25			1.1			1.5
14.35	1.1			1.1			1.6

28.0		1.8			1.7			1.6
28.3		2.0			1.8			1.7
29.0		3.5			2.5			3.0
29.7		3.9			4.0			4.2

My ideal shack location is with the 26' of coax, the 41' is secondary outside location (fair weather).

What should I do for the 40 and 10 meter wavelengths to tune? I think I leave the 20 meter portion alone? Once the 20 meter is tuned, the 10 meter falls into place supposedly but … 
Why do my values vary so much? I sort of see a pattern. I want to physically tune the antenna and not rely on the internal Elecraft ATU. I want to maximize my QRP.

Inverted L configuration with 2/3 vertical and 1/3 horizontal.

Equipment:
LNRPrecision EndFedz EF-10/20/40KMII Antenna
Elecraft KX3, ATU installed but disabled (not bypassed).
LMR240UF for all coax
MFJ870 Grandmaster SWR meter
All frequencies tuned using FM option at 5 watts
I don't have an antenna analyzer, yet.

Just like in woodshop, measure twice, cut once! Again, NEWBIE advice much appreciated.

TIA,
Dave, K6WDE