Search "how much paint" on the RV-10 forum. Several actual used quantities.
Just use the ratio between a -10 and a -7 wing area and you will have as good an estimate as you are going to get. There will be a large variation depending on the equipment used, skill, complexity of the scheme, and just the phase of the moon.
Rans S-20 Raven 796S Now flying (slowly)
RV-6A 596S flying since '99 (Sold)
HP-18 5596S flying since '89
RV-10 996S tail, quick build wing and slow build fues., - dual Skyviews with complete system, two radio and not much else. Interior completely finished with Zolatone. CF plenum, interior complete. 1624 lbs, FLYING after a 21.5 month build.