You are lucky to have had any cherries by now. Many people wait 4-5 yrs for their first fruit. If you remove the 3/1, you may have to wait yrs for any replacement to bloom. Keep the 3/1 and buy another tree. Bing is a very good pollinator for Rainier. It however is prone to split in rain, as is Rainier. A self fruitful variety like Sandra Rose, Sonata, Lapins, Skeena, or Sweetheart would be a good pollinator for Rainier, if they bloom together, and would not need another to pollinate itself. Bing and Rainier do bloom together.

Sweetheart on a dwarfing rootstock like Giesla 5 blooms as fast as anything. It also matures later, which I think gets closer to your dry season. But it can overbear, giving small fruit of inferior guality. You solve that by severe pruning to remove fruit buds and force vegetative growth.

The final size of your trees depends on how much you prune.

The Fruitnut

Skeena is another self-fruitful variety which ripens late in the season. It sounds great in descriptions, though I don't know anybody who has tasted them. Both Skeena and Lapins are described as crack-resistant. Relative ripening times may differ from those cited for this California supplier (Lapins may ripen closer to Bing in some climates).

A (non-self-fruitful) traditional Northwest late-season variety is Lambert, which is large, firm cherry with great flavor. It is inter-fruitful with Rainier, but not Bing.

Here is a link that might be useful: Skeena and Lapins cherries

Where can you buy a Rainer Cherry tree in the Seattle Tacoma area?

Todds Nursery in Puyallup (near Orting) usually has a very good selection and good prices on Rainier Cherry trees.

i was wondering if a dwarf stell cherry tree would work to pollinate a rainier tree

Hello! My question is, Will two rainier trees cross pollinate? Do I have to have a Third tree? If so, does it need to be a different variety?
Thank You!
BTW: I live in Eastern Colorado