My PNA is running WinCE5 on 372MHz CPU and have 64MB ram. There is Primo 2.0 version in it, 9.6.5.306142, but you can use any older, only must be steady. I'm using large DEM file (EU Nasa), but i don't use fda fpa nhr files, and don't have any problems with it.
If you want Igo with low resources, do NOT use: skins, branding, TTS-s, no ux files, no gfx, etc. Only CLEAN Igo. My data.zip is only for 480x272, in your case put 800x480. Megris edition have excellent data.zip and stable exe for that resolution (9.6.5.245577).