I don't necessarily agree that tapering the aft half of the bimini looks better. I've seen it on a few boats and I think it looks a bit odd. It all depends on the boat and the design of the installation
I suppose. I have a canoe stern Valiant and all of my bows are the same width. Looks fine to me.
A significant benefit to making all three bows the same width is stowage. The bimini collapses to a fairly compact size and it's easier to make a cover for it.
If I were you I would attach your bimini to your pushpit. No new fixtures on the deck
, less clutter, etc. It's a matter of geometry; if can have a larger bimini if the frame goes down to the deck
, but it will be more unwieldy and less attractive.
A few things I would keep in mind as you design it:
If you're ever going to add posts to your stern for a wind generator
cluster, etc., make sure that you design the bimini so that you have vertical clearance for these.
If you are going to redesign the dodger, and are going to have a connector made between it and the bimini, make sure the front edge of the bimini is at such a height that it provides for adequate slope to clear the boom end.
Consider carefully where you're going to run the support straps so that they clear rigging
and provide adequate access to your side decks.
Don't let the installer use brass clips for the hardware
. For the support straps, design a "soft shackle" arrangement so you don't have any clatter when the bimini is buffeted by wind
If you have a window put in, make it big enough so that it's actually useful. I have been on tons of boats with tiny windows that don't let you see a damn thing. It's also nice to have the cover for the window permanently attached with ties to hold it rolled back so you don't lose it.
After the installer has left, go back and check all the hardware and mountings for tightness. A not quite tight enough allen screw in one of the fittings can lead to damage to the fitting or the frame.
Go local and make sure your vendor is willing to return promptly to make adjustments after the installation
, because they will probably be some required.