Not sure I'm following this exactly. I spent some time on The Google trying to find examples of deck rigging - hard to find, and pics are really small.

Steve:
I'll pull out a couple of boats later this morning and snap a few pics. Not 'perfect'examples - I keep thinking of changes with each boat - but they might help.

On the commercial boats, it looks like they're splitting the rigging into bow and stern sections so they can use a single length of bungee in each, lacing it through the padeyes.

I'm more concerned with the perimeter safety lines, which are never bungee (elastic shock cord) on well-rigged boats. Anybody who has grabbed a shock cord instead of the (adjacent) deck line during a rescue will tell you that bungees don't work well for handholds!

get a 30-foot (or whatever) length of rope, have it spliced together into a big loop

You'll need to adjust the lines as they invariably stretch after a few uses, so splicing wouldn't work very well, IMO.

Then (as you described) attach a length of rope at the bow like a bridle to use as a tensioner.

Inner loop of each webbing fastener would then be used for lacing bungee hold downs, as shown in Dan's pic.

That would be an excellent system - webbing double loops with the fastener between, the outer loop for the deck lines and the inner for the shock cords for gear.

For the rear deck, there are also arrangements that use line for attaching gear.

One ongoing problem for me has been the optimum spare paddle attachment system. I've been convinced that a paddle bag (Nigel Foster style) on the aft deck is a good solution. Spare paddle stowage, location for chart and deck compass, and possibly items like GPS, waterbottle, paddle float, and pump are things to think about when deciding on deck rigging.
Obviously a surfing boat will have different gear - probably no gear at all - on the deck than a bout for touring.