[grobdriver]

You can bet that California police will be watching those border areas for cars that are loaded with heavy stuff

Well screw that then - we'll take the RV-6.

Now gotta figure out how much 2,000 rounds of 5.56, 2,000 rounds of 45, 2,000 rounds of 9 weighs...
Oughtta be no problem if I leave the wife home!

[Charles Martel]

Now gotta figure out how much 2,000 rounds of 5.56, 2,000 rounds of 45, 2,000 rounds of 9 weighs...

Multiply accordingly, then tally up and add a bit for packaging weight:

9mm Luger
Hornady 115gr JHP/XTP
Rounds per pound: 38.10
Weight per 100 rounds (lbs): 2.63

.45ACP
230gr Winchester Ball
Rounds per pound: 21.33
Weight per 100 rounds (lbs): 4.69

.223/5.56X45
(milsurp) British Radway Green SS109 63gr
Rounds per pound: 37.21
Weight per 100 rounds (lbs): 2.69

Guesstimate: Roughly 60 lbs. each for the 9mm and 5.56 and close to twice that for the .45. You may need a bit more runway than when your wife is aboard.