Barring bad luck it appears Charlotte has obtained her goal of a home of her own. Mr. Collins is greedy and she is frugal with a mercenary eye towards the future. There is every indication they will do the most with what they have financially and I have nothing against it unless they fall into greater arts than she already applied to reel him in. However I can’t dismiss affection as insignificant towards a happy marriage as easily as Charlotte because of the integrity issues made by Lizzy (22, 24) but I think it also does speak to an advantage of the match you raised—that Mr. Collins would not mistreat her which I agree was a real danger for women:

Emotional warmth was a reasonable guarantee of considerate treatment, while a pragmatic choice maintained or improved one’s position in the world and secured the long-term support of family and friends, whose backing it was wise to preserve against the possibility of male authoritarianism. Thus, the key to a successful match lay in the balancing of these two elements. In a non-divorcing society, the Georgians fostered the prudent romance, for in Samuel Richardson’s words, ‘Love authorized by reasonable prospects; Love guided and heightened by duty, is everything excellent that poets have said of it.’

The Gentleman’s Daughter, Women’s Lives in Georgian England, Chapter 2, Love and Duty, page 86 by Amanda Vickery, 1998

Charlotte has no affection for him as well as no personal respect and Mr. Collins views of women makes his respect for her questionable and I am not sure there is any text to support he is even capable of genuine affection. I think he was quite ready to throw all his devotion and affection at Jane’s feet (15) before Mrs. Bennet burst that bubble. His affection for Lizzy is described by the narrator as “quite imaginary” (20) and Charlotte believes his “attachment to her must be imaginary” (22). Without any real affection between them it seems there is only duty to guide them and considering Mr. Collins views of his duties as a clergyman (18) I can’t count on his ideas of duty to his wife being without the self-centeredness attached to all his views. So without a reasonable guarantee of considerate treatment bought by some level of affection how can you be convinced Mr. Collins will always treat Charlotte well?

I think it is possible Mr. Collins’ regard for Charlotte could disappear quite easily if his pride was engaged. His so called violent affections for Lizzy quickly turned into compassionless angry pride after he realized she was truly rejecting him, “the possibility of her deserving her mother's reproach prevented his feeling any regret” (20). When Lizzy visits Hunsford he exhibits an unforgiving animosity towards her, “he addressed himself particularly to her, as if wishing to make her feel what she had lost in refusing him” (28). Mr. Collins has the disposition and being male he also has the power to make Charlotte’s life quite miserable if he wished to do it.

There is also no guarantee Charlotte will always treat Mr. Collins well or with an appearance of respect and it would not reflect well on her—men had far more leeway in their behavior than women. I think Charlotte depends on her own strength and abilities to manage him and to bear with him over the years. I am sure it is her intent to manipulate without his knowledge, when possible when most needed to redirect his foolishness but I just don’t think it is an easy or happiness promoting task, especially for a lifetime. She may continue something like Lady Elliot in Persuasion:

Lady Elliot had been an excellent woman, sensible and amiable; whose judgment and conduct, if they might be pardoned the youthful infatuation which made her Lady Elliot, had never required indulgence afterwards. She had humoured, or softened, or concealed his failings, and promoted his real respectability for seventeen years; and though not the very happiest being in the world herself, had found enough in her duties, her friends, and her children, to attach her to life, and make it no matter of indifference to her when she was called on to quit them. (P, Ch. 1)

Children may bring Charlotte some happiness but I can foresee they may also bring many differences of opinion on parenting between them. “The subjection in which his father had brought him up” (15) may likely guide Mr. Collins parenting and I hate to think what demeaning foolishness from Fordyce’s Sermons he may try to instill in girls. Surely Charlotte could not sit idly by for that. For now Charlotte does treat Mr. Collins well, if manipulating him can be so described, at least he appears happily unaware of the deception. However how these negative feelings will influence her behavior towards him in the future is an open question. Unfortunately I think it is in human nature to despise a person so easily manipulated. There is a possibility familiarity will only breed contempt in Charlotte and she could turn to making sport of him (aka Mr. Bennet) or just being disagreeable in some other way.