I use a 2610, but not in my Saab, as that has built-in SatNav.
The 2610 is used and mounted in an XC90. I'm not sure where I would put the 2610/20 in the Saab. For starters, the power supplies are hidden away in the ashtray and armrest. I guess the armrest power supply is a no-no as that would obscure the speaker. The ashtray has to be the source - or you could get an extension lead for your lighter socket - easily available from eBay etc.
As to the mounting of the actual unit - forget the bean bag - use the temporary sticker and mount. The further forward you can get the unit, whilst still being in arms reach the better as it will have a better 'view' of the satellites. In the XC90 there is plenty of relatively 'flat' space to mount it, so it sits pretty centrally within reach of both front seats.
If I were to fit it in the Saab, I think I'd go for a power extension lead and feed it between the trim and underneath the steering wheel to finish somewhere above the drivers footwell near to the drivers door. I would use cable ties and self adhesive velcro to hold it all in place. Plug the unit into that source and run the cable around the edge of the trim - mounting the unit itself on the drivers side edge of the dash - it should be possible to get a reasonably neat 'installation' like that with very little wire showing.
to replace the ashtray with the shelf. This way you can plug in the speaker no problem. I am playing with positioning the unit so it does not block the SID...I 'll take some pics once I find the perfect spot