If you remove and run without those caps, grease will run out of the bearings. The cap is permatexed to the hub in addition to the bolts to prevent this. Shorter headed bolts should be Grade 8 or better and are probably a 14mm x 1.0 pitch (coarse) - the ones in there are in quite tight and you should remove one to get the proper length.

I’d still lean for boring the wheel out slightly, even at home since it is so close. As the wheels are not hub centric, if you are off a little, it won’t matter.