After reading the "Funniest Build Injury" thread, I'd say order lots of bandaids!
I think I remember a thread just like this a few months ago. You might try a search and see what comes up.
if you are sure you will get to your tanks fairly quickly, get some proseal
nutplate rivets
a larger selection of extra aluminum sheet material
if you wanted to upgrade your tank caps now would be good time to do it.
the whole enchilada of needed stuff for your build of the tank- fuel level- float or capacitive? venting, possible expansion bungs for safeair or other tanks, lights if you don't want to wait for a possible new light to come to market before you are ready. pitot tube eh, flop tubes
check web page journals for modifications other people did, decide if you like them and order whatever parts you'd need for them.