I'm not very good at using the editor but I did put together a scenario to figure out BGs. Note that our all units are all regulars, but then so are theirs...
Observations:
1) MoWs appear to take about one HP off each BG for each bombardment. Occasionally two, more often none.
2) BGs usually take one HP off a cavalry, occasionally more. I'm surprised at how infrequently this happens and wondered if I set up the stats wrong, but I can't see how. Perhaps I don't understand exactly how bombardment works.
3) BGs do not move! Therefore the barb capital is all

we have to worry about. The rest is standard stuff.
4) BGs will not bombard full-strength cav armies. They don't even attack MoWs or regular cavs! ! What's going on? Are they paper tigers? Have I set this up right?
5) A cav army can easily take down 1 BG before it needs a rest. 2 if it is lucky.
6) Ordinary cavs make a great combination with MoWs. The MoWs take HPs off and the cavs move in for the kill.
7) Since BGs have the highest defensive strength, they always get set up for MoW abuse.
8) It takes about 2 cavs to take down one full strength BG w/o MoW support.
9) MoWs cannot kill BGs. Do they only have sea lethal bombard?
Conclusions:
1) Assuming I have set up this scenario properly, MoWs are of limited use. We need control of the waters and protection for our transports but that's about it. Oh. And don't forget the GA

2) A classical land-and-absorb the punishment technique is probably the way to go until we get to the capital. We are probably facing SID-level unit production and support though.
3) I see no reason why we should go looking for IA units. Steam and Industry for production, perhaps, but no units. Aside, possibly, from marines.
4) Cavs are indeed the way to go. I admit it. I was wrong

So much so that it may well be better to get to MT before Astronomy.
5) Leader farms
The scenario is attached. Save it in your Conquests Scenarios folder, then load it with "Civ Content" from the Main Menu.
The ineffectiveness of BGs really really surprises me. Can anyone see what I may have done wrong? OTOH, I have never seen an AI arty unit actually bombard except defensively so maybe it's true.