I think it's all pretty standard. I would consider any I've seen not light at all. Some times you see alumni mum tubes used and those are light and you can bend them by pushing on them. When joined in a proper frame and anchored to the hull
frame is plenty strong if properly constructed. They can take gusts to 60 knots. Above that you add enough windage that the force of that will move the boat
or rip the fabric
In one inch you can get it .065 or .049 gage. I don't have numbers handy on 7/8 th inch. You can get 304 stainless or 316 stainless. In fresh water
304 is perfectly fine at least I think so. 316 does cost more. 304 is stronger and if you cover it with fabric
so you can't see it maybe it's not a bad choice and is used. 304 shows surface rust in salt water
and you need to stay on top of it. eBay is great at this bait and switch. They tell how thick it is then not tell you it isn't 316 yet is priced far less than 316. Cheap
304 stainless is in fact far cheaper than 316.
If you are going to spend more money
on tubes get the 316 tubing and the fittings too. It will work
grreat and look brand new 20 years later long after the fabric has been replaced twice.
Before you say it's "very light" I think it would help to go over the application you have in mind. For a bimini top only you really don't have advantage with using heavier tubes. Sronger does not always matter. The fabric is still far weaker. If you make the frame so it is solid and not held up with straps and such you can make it very rigid.
If what you have is a folding type arrangment I would switch to a rigid frame before I increased the size of the tubes and make it heavier. If you have aluminium then by all means the change will be dramatic. Light isn't allways bad.