Another consideration (sorry to pile on the bad news), is that the market here is very hot anything sub $700k going up to about $1M, because that's still considered entry level. Once you get into luxury range, which for here starts just below where you're talking about with your ARV being $1.45M, it's not nearly as strong a seller's market. To fetch $1.45M you'd have to have extremely top-end finishes, at least 3-4 beds, garage, flatiron views, good location (which "The Hill" is definitely not, you do not want to be there with a family unless farther over on the Chataqua side or over Rose Hill way, anything 1 block from CU will be student housing). To compete in the $1.45M range you're talking $300-350/ft2 construction cost, not exaggerating. You need to be looking more in the Whittier/Newlands/North Boulder area for your plan, but you likely won't find anything near that price in those areas unless its a total scrape. You will probably need to go more distal like Gunbarrel (maybe, also getting expensive) or out east to the L towns Lafayette or Longmont (Louisville already too expensive).
Mindy is not exaggerating on 1,000 years to get a permit (okay, she's slightly exaggerating). Rentals are required to comply with the rental housing license program which means inspections which means you can't just make a porch into a bedroom without approval (you may be able to get away with it for a while but the enforcement division is real and the fines are too). Popping the top or adding anything beyond 500ft2 means going through the dreaded "site plan review" process which is based on the LEED points program/ IGCC (green construction code) and you'll end up spending a fortune on insulation, solar, high E windows and appliances, etc. You may have to comply with the new "smartregs" program which means many of these same efficiency upgrades just to get your rental license. Boulder is a great place but you've got to be on your A game here. I guess they figure since we have the highest percentage of residents with PHDs in the country we all must have the requisite PHD required in order to navigate the maze of regulations.
Longmont is really up and coming; the SW side closest to Boulder is really nice and has good schools, quick access to trails, etc. Longmont has many of the advantages that Boulder has but property is still relatively reasonable by comparison. Lots of good stuff planned for Longmont so long term I think there's a lot of potential. Demographic is shifting with a lot of young families ending up there; bike paths going in, breweries galore, more and more good restaurants opening, etc. plus Boulder is only 15-20min away. Just avoid the NE end of town, generally speaking of course. It will likely be "transitional"/stabby up that way for a while, although there are some nice pockets up that direction which are totally fine right now. Lafayette is also up and coming, Erie too.
I think you should abandon this plan because the location is not right for what you want to do. Comps in that area do not support an ARV of $1.45M. Also there's no way a 1.3 acre lot exists near where you're talking at that price, so it must be 0.13 acres. A 1.3 acre lot that close to CU and downtown would be closer to $5M.
Keep looking around. You mentioned Denver was an option, and you'll have a lot more to choose from down that way (I like Golden a lot regarding Denver suburbs). Good luck!