from years of experience working on heavy duty trucks with air brakes and air bags, there is no leak proof system..
but I'll share some tips to getting close, possibly close enough to run with minimal issues without an onboard compressor..
keep in mind that you may want to maintain enough ground clearance to get home in the event of total air loss
minimize the number of fittings and length of plumbing.. adapters, tees, bushings, etc all add leak points..
use high quality compression fittings without swivels.. push-lock and swivels leak..
leak test everything at maximum rated inflation, soap n water, snoop, etc.. repair or replace as necessary..
two home runs from each bag to it's own schrader would probably be the least amount of connections and shortest runs..
and as mentioned above, allows for balancing loads as well as launch
don't allow bags to deflate completely.. this distorts and stretches mounting seams on the ends of the bags..
may also consider using dry nitrogen, denser gas escapes less through rubber, more stable pressure during temperature changes, and dry gases contain less contamination to promote corrosion and oxidation on metal parts..
I have this little rig for reservoir shocks, works like a champ and lasts a looong time.. notice the Schrader 556 low-loss valve on my gauge manifold.. the manual valve stem depressor t handle allows precise pressure management without the 'pssst' loss when removing push-on valves..
pro tip - although valve has a hex, these handle much higher pressures than needed for automotive use and can be adequately tightened by hand so not to distort the brass seal washer
good luck!
