I have run very wide tires on very narrow rims with no problems whatsoever, and I'm #225
(60 mm Super Motos on 19 mm rims)
I think the rim width recommendations are for optimal handling, not necessarily a safety recommendation.

Likewise, I generally run wider tires below the recommended pressure. For example, I have some 38 mm tires that say 55-85 psi, yet they ride great at 45 psi.

Don't get worried about the rim width. When you wear out the brake surface on your Open Pros (10,000 miles or so), consider replacing them with a 23 mm wide rim, which are easy to find. Velocity rims have lots of nice options.

For tires:
Lightweight "supple" tires have fantastic ride qualities and handling, but can be flat-prone: Compass tires (made by Panaracer), some performance tires from other manufacturers
The Panaracer Pasela is a great all-around tire for road and light off-road. They come with a puncture belt and are cheapish. They ride more stiffly than a "supple" tire, but last longer too.
The Soma tires are also made by Panaracer. The New Xpress is lighter/more supple than a Pasela, but still durable. The C-line has no puncture belt and therefore is even lighter.
The Schwalbe Marathon line of tires are made to be durable to extremely durable, but they have a poor, stiff ride. There are many Marathon variants. Some folks love them, but I prefer a lively ride. I'm not afraid of fixing flats.

Your Sam Hillborne should clear 38-42 mm tires, and I think that size provides a great ride for us larger folks.