I have never ridden or built a low ridder so I can't help much. (but am sure some one who can better advise you will jump in) If you get a chance to test ride a point beach, they are great for less then $200 bike. I just don't know if even with the bent seat post, you would be back far enough to be comfortable. Once your ridding a MB, it is very different then the ride you have on the same bike with out the engine. (makes shopping funny) For a MB, I like to be well behind the peddles unlike a bike where your more over them. Might just be me. The banana seat is really a great option (I just cought your joke)
I was admiring nogoodnic's ride,
GT Kustom Kruiser Deuce Cruiser Bicycle. nogoodnic told me that it had an extra 4" in length. The thing I like about it is perfect fenders, good looks, double down forks and Apehanger handlebars. It is second on my list of bikes to buy. I have not been on one so I am just talking ascetics. Looks to be a one speed, coaster brake with no stock front brakes from that pic though. (
Schwinn deluxe 7 is #1 and around $700)((..But Honey, I need another bike. the 8 we have now just don't cut it)
Drop him a PM or email if it looks like what you want. Really is a great looking foundation for a MB.
On the higher end, but below the Deluxe 7 are
felt bicycles. Some great choices and local dealers will drop from the MSRP (Manufacturer's suggested retail price) a good bit. But they are still up there around $600's (check out the "MP" really cool) A lot of their bikes are just a tad to high for me, so might be a perfect fit for you. Thing about going with a good bike, is you then have a good bike. Although it is big cash.
...Could build a family
Schwinn: 2009 Tango TandemMB