1v1 Hourglass Improvements

but I find it very aggravating when I am trying to play hourglass as a solo like always and another ship (especially a larger crewed ship) enters the fight and either sinks both ships which ruins the entire point of the fight

The point of the fight is to win a PvP match. If they sink the enemy ship for you, good you earn a win. If they sink you, Oh well a lose.
Sinks both ships, well that PvP for you. What to be mad about? You wanted pvp did you not.

or teams with one ship and helps them sink the other.

See above. Same results. I do this with ships I see doing hourglass, If Im feeling Athena and see a Reaper, I throw in my support. Same with Reaper if feeling it. Often, both ships attack me :P and I sink.

I feel that there should be a fix to this such as making battle bounds impenetrable by other crews which would solve the issue of fights being ruined or made unfair by other crews.

So your wanting Last ship standing, with less players. :/

I believe that this would help eliminate some frustration that smaller hourglass crews face when ships like brigantines and galleons interrupt the fight and often make it unfair for one crew.

So you want the servers to be more empty, less fighting all together because you dont like to either: A) be the target or B) Earn a free win.
I find hourglass only players to be very confusing. Hourglass is a PvP tool, you search for like minded players to fight in the Open world, and when some stranger comes along to also join, It's suddenly against non-existing rules.
(This why its not a mode, No rules saying what you can and cant do.) as well, you can make situations into your favor..like a rowboat of Kegs :P