I'm sure that you could make some very well represented side doors using thrifty methods and materials!
It will take time, but you enjoy building things and are only going to build another after you finish, so you might as well build doors. Take it as a challenge to prove that making your own doors can be A LOT less costly than just buying factory made. So many people use the excuse, "by the time I was done it cost almost as much and took so much longer that I should have just bought factory doors"... you need to show them the way.
The major cost factors are windows, latches, hinges, and seals. We know that you have plenty of good ideas for great functioning windows (we've seen the sketches); hinges only cost a lot if you use high end stuff; seals can be basic (... but I went with TrimLok and justified it as being trim and seal all in one, no alum to buy, no fasteners needed); latches could be a hard wood double toggle swing bolt with a simple pin on the inside to lock.
I find myself more and more wanting to build a second, but go the total polar opposite from TPCE. Something like
Lilgription's OSP, or what drew me to the forum, the weekender. The OSP has cargo utility as well.