The factory extended slide stop lever in my Glock 17L is positioned just like yours... I wouldn't worry about it...
"While the anti-gunners seem very concerned about the "one life" that your firearm might take -- they are not very concerned about the lives it will save." Jon H. Gutmacher, Florida Firearms - Law, Use & Ownership
As to barrel length, the G17 is of legal length as it comes from Glock (114mm) A 107cm barrel would be a little unwieldy at 42 inches.
If you really want to fly, get out of the plane.
Member: NRA, IDPA, GSSF
GLOCK Certified Armorer
G22 Gen 3, G17 Gen 4, G17L, G17 RTF2 Gills, G20 w/ATS Sights, G19 Gen 3, G19 Gen 4 w/Trijicon Night Sights
G26 w/Glock Night Sights, G27, G36, G42, Ruger SR1911, Ruger Mark III 22/45, S&W M&P 40 Shield,
Mossberg 500A Persuader, Rock River AR-15, Marlin XT .17 HMR, Mossberg Maverick 88 20 Ga.