If you have trouble getting brass too hot, you are probably just... getting it too hot.
Silver brazing/hard soldering on thin materials is not different than doing thick stuff,
except the temp gets where it needs to be faster. Just saying you shouldn't have any
problems with it.
45% silver and .032" brass sheet to .005" brass shim stock.
45% silver and two pieces of .024" brass sheet.
56% silver and thin brass sheet to thin wall brass tube.
Have at it, and practice a bit.