Bed bolts and bed frame hardware are relatively inexpensive. e.g.
http://www.leevalley.com/US/hardware/page.aspx?p=40445&cat=3,40842,41269

 

It would weaken over time. +1 for bed bolts.

 

The cross dowels would be much better than end grain. That's how I attached the short stretchers on my work bench and they have held tight for 3 years now. I used 1-1/4" diameter maple dowels.

But bed bolts are probably better, or at least as good and a lot easier.

 

Spend the big money for bed bolts. Lag bolts will strip out in end grain. If you go with lag bolts, definitely put a cross grain dowel in.

Depending on the thickness of your rails, you might be able to inset a dowel from the inside of the rail and not have it show from the outside of the bed.

 

Bed bolts for sure.
Bill

 

No.

Confirmats might be better.

You can use standard carriage bolts and square nuts
but drilling a hole in the back of the rail for access to
each nut. I'd leave 1/4" of material after drilling and
with 1/4" carriage bolts 3/4" rails seems to thin -
I'd go with 7/8" plus which generally means getting
good 5/4 stock for an 80" rail.

An alternative is tension rods running 2 to a rail in
grooves. My workbench is built this way, more or
less (got the idea from Lee Valley), and it's the most
solid joinery under racking you can ask for.

 

I have used the method described by Loren incorporated with a tendon on the end of the rail inserted into a mortise in the post. A very solid method. I used 8/4 for the rail planed to 6/4 with a 1"x4" tendon.