By the numbers; several years of contender variety peach grown here has had a pH of 4.01/ 3.87/ 4.25/ 4.28/ 3.84. ie this fruit needs acid to make a successful wine. Red raspberry from the garden has a pH of 3.04/ 3.19/ 3.46/ 3.01/ 2.93/ 3.11 therefore it has excess acid to contribute to a low acid fruit.
What you are suggesting is the style of wine i put together. I try to maximize the flavor impact and make 100% fruit wine (no or minimum water). This means usually taking a high acid and low acid to reach a target someplace near pH 3.5.
Other considerations; the TA of the peach has ranged from 0.99% to 1.50%. These years of red raspberry ranged from 2.18% to 2.82%. Both of these fruits are high TA which means that cutting the dry matter in the wine (fruit solids) might be appropriate. My by the numbers calculation might use one to two kilo of water for every kilogram of fruit. A dry wine having 1:2 ratio and a finished wine back sweetened at 1.008 having 1:1 or my style with a higher TA I would back sweeten to 1.015.
What you suggested is very doable. The first consideration and again final consideration is the flavor pleasing to you?
The blend I made was peach with rhubarb ,,, low acid mixed with high acid. I was amazed if I tested back sweetening to 1.008 it tasted/ smelled like store bought green peach but with the sugar at 1.015 it smelled and tasted like tree ripe peach. The guess on my part is that peach with raspberry will be dominated by raspberry flavor.